Hoop snares - they work in light soily or sandy ground. The wire must be high tensile. the rabbit hits the snare which is attached to the hoop.
With the wire being high tensile, it just bends and springs back, if it wasnt high tensile it would bend and not spring back, the hoop would come out.
Dont worry, the hoops definatly work no matter how it seems to the untrained eye