Kirb-Perfect Features. Build a perfect shower curb every time with the new Kirb-Perfect. Use with or without a 2 x 4 wood curb on any size shower. Kirb-Perfect is designed to be used with a pan liner. Easily cut with hacksaw, PVC cutters or grinder. Economical, lightweight non-rotting plastic. Works great with the Quick Pitch System. Kirb-Perfect Kit includes: 2 side panels - 5-1/2" H x 30" L. 1 top panel - 4-1/2" W 2"x 30" L.