Inspection Plates Inspection Plates-lids are easy to install and give great access into the tank. The inspection plate comes with an easy to install collar that attaches to the tank. ??6 screws tie the collar into the tank, and the lid threads right into the collar. ??You may want to consider a light bead of silicone caulking under the collar for an ultra-tight seal.?? The inspection lids are used on most any type of plastic tank. ??Common uses are for RV, Marine, and Food Service trucks. 8″ Inspection Lid Clear??Features: Inside diameter 8″ Outside diameter of collar 10 1/8″ Hole cut size 8 1/2″