StormDrain FSD-3001 Catch Basin Drain Box Seal and Nut The only true watertight seals on the market today Accepts 2", 3", 4" Sch. 40 sewer and drain and corrugated pipe 4" seal fits in both the 12" and 20" plastic D-box Made in the USA Works with FSD-3017-20BKIT and FSD-3017-12BKIT