Let the critters remove themselves with this system. SP55 is perfect for fox and grey squirrels and similar sized rodents. It's extremely simple to use and very effective. SP55 consists of one E50 excluder and two SPT55 repeating traps (with two trap doors). Attach the E50 excluder over the animals den opening with the mounting wings. Slide one of the SPT55 repeating traps over the E50 and hook into place. As critters exit, the excluder will direct them into the repeating trap. SPT55 repeating traps have trap doors at each end to allow you to caputre animals both leaving and entering the den. To remove trapped animals, unhook the SPT55 repeating trap from the E50 and replace it with the other one included with this kit. This kit has a 5 x 5" opening and is desinged to be tacked up over 5" wide or smaller openings.