This is the small-sized Safeguard Multi-Catch Extender which measures 24"L x 3 3/8"W x 3 3/8"H. It has two (2) interior spring-loaded doors and a hinged rear door for ease of releasing captured animals. The Multi-Catch Extender fits into a Safeguard one-way controller (#53120) as shown, and its' purpose is to allow the multiple capture of squirrels and allowing them to move "away" from the entry point so the initial spring-loaded door is NOT BLOCKED. You can easily catch 2-3 squirrels in one setting with the Extender. Can be used for gray squirrels, as well as flying squirrels.