For Mice, Shrews & Voles Humane and effective, these well-made metal traps catch animals alive (see our bait kits), for release elsewhere. Havaharts are field-proven and made to last. Built of heavy galvanized steel wire, these pre-assembled traps feature an adjustable trigger release pressure mechanism which makes them easy to bait and set. Professional Traps are built for the constant use, high demand needs of conservation agencies, humane societies, animal control officers and professional trappers. The doors are spring-loaded and made of steel wire.