Slumber Pet Baby Bumper Crate Kits. Baby Bumper Kit Converts Crates into Safe, Cozy Spots. Perfect for new puppies or dogs that you just want to make comfortable and feel safe. Cozy two-piece Baby Bumper Kits. Soft and cushioned and made to fit standard crate sizes, the fitted mat and bolster sets come in Blue or Pink. Easy to attach, may also be used outside crate. For Wire Crates in the correct sizes, X-Small measures 17 3/4 in L x 11 3/4 in W. Small measures 23 3/4 in L x 16 3/4 in. Medium measures 29 3/4 in L x 18 3/4 in W.