The standard design neck seal found on most drysuits offers a {10in | 252mm} mounting diameter at the base, three different latex thickness options, and a variety of choices for neck sizing - see sizing chart below. As a general rule, the seal opening should be trimmed to be no smaller than 80% (i.e. maximum of 20% less) than your actual measurement of the relaxed neck circumference, tighter than that could cut off blood flow to your brain.
Latex Thickness Options:
- Flexible (FD): 0.5mm to 0.7mm - More flexible with more stretch than the standard
- Standard (GD): 0.7mm to 1.0mm - Usual thickness found on most seals
- HeavyDuty (HD): 1.0mm to 1.4mm - Thicker, thus more durable, but less comfortable