DPM PF-T8S-2.9 3-1/2” Hole Saw 8 Stud Penetration Single Sided Fitting is used for 2-1/2” Nominal Pipe. The studded penetration fitting includes a flexible acetal back plate that seals on flat or curved surfaces up to 24” in diameter. The penetration is secured with stainless 1/4-20 flange nuts on the sump interior. Boot material is a injection molded rubber called Alcryn. Assembly includes Series 300 all stainless clamps. It includes series 300 stainless clamps,stud seals and flange nuts.