This might be of interest to the kayak sailors out there.
I was looking in West Marine for small blocks (pulleys) for my kayak sail, to see what was available and if they might have a suitable replacement for the ones I have, which have gotten a bit stiff and corroded. A staff member described something that might work, but she couldn’t remember what it was called, nor could she find it in the store or on-line while I was there. But after some time spent searching for it afterward, I found it. I have purchased a set, and gave it a try yesterday:
Shocks™ | Ronstan Sailboat Hardware US
They have no moving parts, but can be used to replace the block (pulley) on the uphaul/forestay line and the sheet. They worked well. They felt as smooth and precise when adjusting the lines as the old blocks. And they are a lot smaller and lighter than the blocks they replaced. I am quite pleased with them so far. If you find your blocks are in need of replacement, these might be an option worth considering.