The Koro Rodent is the original rodent trap designed for use on weasels. It was soon discovered that they working very well on other species as well including the red squirrel and for rats as well. The Koro Rodent is made of .187 dia. mild steel with a house made spring made of music wire. The Koro Rodent measures 3 7/8”L x 3 1/2”W x 3 3/8”H. The Koro Rodent is available in its original form with a trigger (dog), that wraps over the strike arm and fits into the hole located on the pan or the new easy latch trigger system that makes setting a breeze.