This window rubber is suitable for fitting either Perspex, glass or acrylic into boats, cars, vans etc. It allows for easy replacement of damaged windows. Remember to order the filler strip to hold it in place. To find your required size measure your glass and panel thickness and look up the closest size on the table. The rubber will seal approx -1mm (e.g. 4mm glass will seal in a 5mm gap). It is recommended to bed the rubber in with a silicone sealant.