The Storm Sentinel Drain Protection Inserts help companies comply with Stormwater Pollution Prevention Plans and Stormwater Best Management Practices by protecting your storm drains and catch basins. It is the sure way to catch oil and sediment headed into storm drains and sewers. Equipped with an oil-absorbent media in a screened bag, the Storm Sentinel guards against any potential discharge.ENPAC's enhanced design has increased the surface area for greater sediment retention while decreasing the depth of the unit in the catch basin.Inserts fit round catch basin's from 27" to 29" in diameter. Custom sizes available.Up to 500 GPM overflow rate helps avoid ponding. Requires no special tools to install. Helps comply with NPDES, 40 CFR 122.26 when used as Best Management Practice in Storm Water Pollution Prevention Plans.TO INSTALL: Remove grate and adjust wire frame to fit in recess. Place insert into recess and frame into corners. Replace metal grate.TO REMOVE: Lift the grate, grab the handle and pull out the insert. No part of the insert extends above the surface.