Using them is also illegal in all likelihood. Don't use them except in a survival situation.
Game running through the snare disengages the trigger bar,and the prey is flung off the ground.
Use on game trails or in gaps through rocks or hedges. Drive upright into ground. Attach snare to trigger bar, then trigger bar to sapling. Construct as for spring snare but using the release mechanism shown. The bait support should be only lightly driven into the ground as it must fly away with the snare.