What I've been looking for.
These are real durable and heavy duty, also visually appealing. The grip is very hard and firm, the texture is ridged, they don't come off when the chain is pulled, and they're far more painful than adjustable clamps. These are not adjustable, and the chain is not detachable.
I'm not sure what metal they're made from, but after having left them in water for a few days they slightly corroded in one area. I'd say they're fine to use in water, but shouldn't be submerged for long periods.
