These are Brass snaps that can be used on any of the flat leashes. Silver is brass with chrome coating. Small is 1 & 1/2" - Medium is 2 & 1/4, Tiny ranges from 1-.1/4 to 2 These snaps get heavier the taller they are so the Large can hold a dog over 100 lbs. These have been tested to that effect. Silver snaps are brass that is coated with chrome so they won't rust, I haven't seen one that is worn off except being drug on the road.