I too thought Si-Tech made the seals for Waterproof, but I can't find anything that specifically indicates that. It occured to me that one company might be owned by the other, so I looked up each company's address in Sweden and they are different. Of course none of that is conclusive.
I prefer the bottle neck shape of the Si-Tech wrist seals. It may just be in my head, but to me it seems there is more contact area between the seal and my wrist/forearm with the Si-Tech seals compared to the Waterpoof wrist seals. Here is a visual comparison with images I culled from google images:
The last time I recall handling Waterproof wrist seals, I remember them feeling a tad thinner and possibly stretchier than the Si-Tech version. But since purchasing my drysuit in 2018, I have only needed to replace 1 wrist seal...so I am happy with the shape and durability of the Si-Tech ones.
I have at least one Waterproof neck seal in our stash of replacement seals we purchased before moving back to the US...prices in Europe are/were nearly half the cost for neck and wrist seals compared to the US.....I am still using the original Si-Tech neck seal that came with my drysuit, so I have no comment/review of the Waterproof one yet. As I think about this, the shape of the Waterproof neck seal needs to be indexed for the extra fold/pleat to be behind the neck, that does not appeal to me all that much but maybe I will find it to be a non-issue in practice when installing it.
Knocking on wood that my seals have lasted this long.
-Z
