The Drawstring Neck Dam, Part Number 510- 533 is the standard neck dam configuration on all SuperLite-17A/B & U.S. Navy MK-21 Mod. O & Mod. I Helmets prior to August,1995. The 1996 Model SuperLite-17A/B Drawstring Neck Dam has had a design change made to it.
The neck chute of the dam is now angled, allowing the helmet to rest in a more comfortable position and lessening front end ride up. It also fits a wider variety of neck sizes.
There are no part number or price changes due to this alteration. As of 8/15/95, this changed part is shipped as "standard" on all SuperLite-17A/B helmets.
THIS NECK DAM IS NOT A ONE SIZE FITS ALL TYPE. IT MUST BE TRIMMED TO FIT
Try the Neck Dam Assembly on for comfort. The blue side must be against your neck. Slide the Yoke onto the neck from behind; spread the opening of the Neck Dam and pull it down over the head. The Neck Dam should be moderately easy to pull over the head and fit snug enough to prevent leaking, but not so tight that it limits or restricts circulation. If the Neck Dam is too tight on the neck or too hard to get over the head, the Neck Dam MUST BE TRIMMED. Trim 1/4 inch at a time, as shown, until the proper fit is attained. Do not trim more than 1/4 inch at a time.Do not use a loose fitting Neck Dam. It will allow leakage and possible flooding into the helmet.
If the helmet is to be used by several different divers, we recommend that each diver have a Yoke / Neck Dam assembly that fits them. Each diver must check the fit of the Neck Dam prior to each dive.
If the Neck Dam is too tight on the neck or too hard to get over the head, the Neck Dam MUST BE TRIMMED.
Warning: Diving with a Neck Dam which is to tight can cause restricted breathing and can lead to the diver blacking out. Always check the fit of the Neck Dam before each dive.
Before diving a new helmet or one with a new Neck Dam, the Neck Dam MUST be checked for proper fit.