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O'Neill Heat 4/3 Back Zip Wetsuit - 2018

O'Neill Heat 4/3 Back Zip Wetsuit - 2018 4.9 5 10
SKU: ONL4405
Eligible for FREE SHIPPING!

Availability: In stock

Regular Price: $299.95


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Cleanline Staff Member Matt Cleanline Staff

Matt Says:

"The O'Neill Heat 4/3 Wetsuit has been updated with a classic look, but this is still the Heat that we know and love. A great mid range wetsuit featuring an exterior fluid seam weld for durability, smooth skin chest and back for added warmth, and a back zip entry for easy on and off. Now that the neoprene has been updated to 100% UlraFlex DS (super light and stretchy) it is a better value than ever. One of the best selling O'Neill wetsuits out there, which is why you can get it in some of the hard to find sizes like XXLS and XXXXL. Great suit!"


The O'Neill Heat 4/3 Back Zip Wetsuit is stuffed with high-end features and materials. Built with 100% durable stretch UltraFlex Neoprene. FluidFlex Firewall in the chest and back make this wetsuit water and more flexible than ever before. The Heat also includes exterior Fluid Seam Weld, redesigned #Q length zipper panel and easy-in-easy-out usability.


  • Thickness: 4/3mm
  • Neoprene: UltraFlex
  • Seams: Single Fluid Seam Welds
  • Zipper: Back Zip
  • Hood: None
  • Model Year: 2018/2019
  • Manufacturers Part Number: 4405

Product Features

  • Back Zip Entry System, RedZone Zipper provides easy entry and exit with a water tight seal
  • UltraFlex, super soft neoprene for superior feel, flexibility and high performance
  • Fluid Seam Weld, 8mm silicone-based urethane sealed exterior with a triple glued and blind stitched interior. Watertight, durable and ultra flexible seam
  • RedZone Zipper, urethane coated, offset zipper teeth interlock to stop leaks and keep water from entering wetsuit
  • Double Super Seal Neck
  • Smoothskin FluidFlex Firewall
  • External Key Pocket with Loop
  • Strategic Seamless Paddle Zones


O'Neill Heat 4/3 Back Zip Wetsuit - 2018 Cleanline can't be beat!Review by BOB BOB
Great suit, and great service as always by Cleanline.

(Posted on 9/25/2019) 2019-09-25
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 Warm and easy onReview by Assateague Kiter Assateague Kiter
This suit is easy to get into and as warm as any other 4/3. I've had many O'Neill suits and hope that this one lasts 10 years or so like the others. The one downside is lots of cold water in the back zipper- this could be avoided if they had a neck pull over like the Ion suit but that is not too easy to get on.

Used this suit today with a 1.5mm O'Neill shirt underneath- 45 degree air and water with 20-35 mph winds and I was warm and comfortable
(Posted on 1/9/2019) 2019-01-09
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 Really surprisedReview by T.C. T.C.
Put on some pounds after back and hip surgery and I wanted an inexpensive suit until I lose some weight and can get back into my Psycho again. This suit fits well, is built well and is very easy to put on and take off. Flushing isn't as bad as I thought it would be. I'm glad to be back in back zips again after trying several chest zips with hoods. Back zips feel better around my shoulders and I can paddle easier. When my Psycho wears out I may keep getting these.
(Posted on 12/18/2018) 2018-12-18
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 old suit blew outReview by rubba dubba rubba dubba
so far so good, fits eccel. , easy to get on and off, O'neil could make the zipper tag line 2 inches longer but no big deal. Cleanline is a pleasure to do business with, recommended them to a friend when he couldn't find the right size. Thanks!
(Posted on 8/6/2018) 2018-08-06
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 EXCELLENT SUIT, GREAT CUSTOMER SERVICE BY CLEANLINEReview by Scott Scott
I recently purchased an SUP board and decided to get a 4/3 Heat so I could try out the board before everything here in Wisconsin turns to ice. I own some other lower-quality wetsuits and have to say I was absolutely amazed at how warm this suit is while not being restrictive at all. The water I was on had some ice floating in it, and the air was about 35 degrees. I fell in once at the beginning of my session and continued on for over an hour and never felt cold.

The back zipper initially let in a tiny amount of water, but let's face's called a WETsuit for a reason! The welded seams are awesome because they're sealed up like Fort Knox. The neoprene itself is super stretchy and, with the help of the friendly Cleanline staff, I found that the XLS size fits me like a glove.

The staff at Cleanline were awesome to work with and the suit came with a personalized hand-written note and a few Starburst candies. A dude who wears an XLS really doesn't need candy, but hey, it was a nice touch!
(Posted on 11/14/2017) 2017-11-14
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 The best wetsuit I've ever hadReview by Neco Neco
I've been wearing o'neill wetsuits for over twenty eight years and this model is by far the best of all. Ultraflexible, warm, easy to put on and take off , and the classic design is awesome. I recomend it one hundred percent.
(Posted on 6/13/2017) 2017-06-13
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 Comfy warm suitReview by DoubleD DoubleD
What a difference a new suit can make! This suit is comfortable and warm. I'm glad I got the back zip because I am over 50 and it is really easy to get in and out. Cleanline sent a bunch of goodies and handwritten note in my box when everything arrived, which was a nice personalized touch.
(Posted on 1/30/2017) 2017-01-30
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 WARM AND COMFORTABLE Review by Brostertado Brostertado
This is my first 4/3 wetsuit and I'm extremely satisfied. I used it the day after Christmas in 58 degree water and stayed nice and warm. I used the size chart hoping to get the right size and mine fits perfect. Worth mentioning, Cleanline surf was excellent to work with. Fast delivery and good service.
(Posted on 12/27/2016) 2016-12-27
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 best wetsuit i have own Review by murph murph
the 4/3 O neil heat way better quality then my previous 4/3 O neil epic. The 4/3 heat easy on and off love the welded seams and keeps the heat in
(Posted on 12/21/2016) 2016-12-21
O'Neill Heat 4/3 Back Zip Wetsuit - 2018 Quality suit, great price, amazing service with CleanlineReview by hilaria hilaria
Perfect suit for the SoCal winters. Firewall interior keeps you toasty in the lineup. Doesn't feel like a 4-3, surfs more like a 3-2 due to the strechy factor of the material.
(Posted on 1/5/2016) 2016-01-05

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Size Chart

O’Neill Men’s Wetsuits — Size Chart

The staff at Cleanline Surf specialize in sizing O'Neill Wetsuits. If you have never tried an O'Neill suit before, we strongly urge you to call us for expert advice on sizing. We do have a size chart available below, but please take it with a grain of salt. For the perfect fit the first time please call and speak with one of our wetsuit experts.

XS5′7″-5′9″125-140 lbs36.5-37.5″28.5-29.5″
S5′8″-5′10″135-155 lbs37.5-39″29.5-31″
ST6′0″-6′2″145-165 lbs37.5-39″29.5-31″
MS5′6.5″-5′8.5″145-165 lbs39-41″31-33″
M5′9″-5′11″155-170 lbs39-41″31-33″
MT6′1″-6′3″160-180 lbs39-41″31-33″
LS5′7.5″-5′9.5″160-180 lbs41-43.5″33-35″
L5′10″-6′0″170-190 lbs41-43.5″33-35″
LT6′2″-6′4″180-200 lbs41-43.5″33-35″
XLS5′8.5′-5′10.5″180-200 lbs43.5-46″35-37″
XL5′11″-6′1″190-210 lbs43.5-46″35-37″
XLT6′3″-6′5″200-220 lbs43.5-46″35-37″
2XLS5′9.5″-5′11.5″200-220 lbs46-48.5″37-39″
2XL6′0″-6′2″210-230 lbs46-48.5″37-39″
3XL6′0″-6′3″230-250 lbs48.5-51″39-44″
4XL6′1″-6′4″250-270 lbs51-53.5″44-48″

Full O’Neill Wetsuit Sizing Chart



If the product is found to be defective under normal use and proper care, O'Neill will repair or replace the product at our sole discretion. The decision to replace or repair a product is made by the O'Neill Warranty Department after receipt of the defective product. At no time does the O'Neill offer refunds. Defective product should be returned clean and dry, postage prepaid. Please include a note with product description, product defects, requested action, return address (be sure to include postal code, especially for Canadian addresses), daytime phone number with area code, customers name and a copy of the purchase receipt sent to the address below.

Suits without a copy of the purchase receipt will NOT BE COVERED UNDER WARRANTY.


  • Products classified as seconds
  • Fading from sunlight
  • Alterations
  • Materials over 1 year (from date of original purchase), or 90 days for accessories
  • Repairs or alterations done by anyone other than O'Neill or an O'Neill authorized repair facility
  • Warranty request without original receipt


Flat-Stitched Products, Glued and Blindstitched Products, and Fluid Seam Weld Products

  • Limited 1-year warranty (from date of original purchase) on workmanship and materials.

Neoprene Dry Suits

  • Limited 1-year warranty (from date of original purchase) on workman ship and materials (waterproof zipper excluded)


  • Limited 90-day (from date of original purchase) warranty on workmanship and materials


For repairs received from the dealer or end user, O'Neill offers:

  • 10 Business Day Turnaround for warranty Stitched Suits
  • 10 Business Day Turnaround for warranty Glued Suits
  • 20 Business Day Turnaround for warranty Fluid Seam Welded Suits
  • 30 Business Day Turnaround for all Non-Warranty Repairs

Repairs are to be returned clean and dry, postage paid. Please include the name and a daytime phone number with area code, return address, product description, and requested action.

Send Repairs To:

O'Neill U.S. Warranty Repair
1022 Bay Marina Drive, Suite 140B
National City, CA 91950
Tel: 1-800-331-1637


We understand that when purchasing gifts, returns and exchanges can be necessary, which is why for the Holidays we are extending our Return Policy so that anything purchased as a gift this Holiday Season is eligible to be returned by the end of January. If you are not 100% satisfied with your product you may return it for a full refund, or exchange by the end of the month of January 2020.

Please make sure your wetsuit fits before taking it in the water. We are not able to take returns or exchanges on used wetsuits.

Please reference our full Return Policy.

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