Clamps are designed for a myriad of tasks like crushing barbs, removing hooks from fish (or yourself!), opening/closing split shot, knot-tying, cutting tippet, etc. Knowing what tasks you regularly perform stream-side will help you select the clamp(s) that best suit your angling needs. Clamps tend to be a very personal item, and like a favorite rod or reel, people have preferences for their clamps. Some anglers like short clamps and others prefer long. Some like straight jaws while others prefer curved. Many like the gold loops/handles and others prefer the stealth-mode black. So, if you lose your buddy's 5” curved black clamp, don’t assume the 4” gold loop straight model you gave him off your vest will clear the air.
If you're angling in salt water, consider using the black oxidized or prism finished clamps which provide an extra layer of protection. For clamp longevity in salt water, rinse your clamps in fresh water and apply a little oil.
Match the clamp to the size of the flies you're using. Generally, the shorter the clamp the smaller and lighter the jaws, and the longer the clamp the larger and heavier the jaws. A 4-inch clamp will struggle crushing a barb on a #4 streamer and a 6-inch clamp will be too large for removing a #22 midge cluster from a fish.
All clamps are made from 410 Japanese stainless steel with a Rockwell hardness of 42.