The 15.90B is a plastic plate that fits underneath the 15.90 flat eye plate to create a barrier between the stainless steel and the surface it is attached to. 

Our range of eye plates are manufactured from 316 Stainless Steel and undergo multiple machining and finishing operations to ensure they have a smooth finish and are free of damaging sharp corners and burs. All of our eye plates are then electro polished to give them as much resistance to the marine environment.