Knock-In Diffuser with Waterproof Seal. Heavy Duty Protection for LED Tape. Available in 1m or 2m LengthsExternal Cross Section: 28 x 11mm Internal Cross Section: 12 x 4mm Diffuser Visible Width: 18mm. Extruded aluminium profile with beveled trim for flush mounting into walls- ceilings or floors. Supplied with a heavy duty diffuser which creates a waterproof seal when firmly knocked into the profile. Designed to protect LED tape when installed into floors or walls where there is a risk of moisture ingress.. led tape profile-waterproof led tape profile-aluminium led tape profile