Super shallow version with a 21mm recess. This lockable triple-sealed aluminium recessed manhole cover from EcoGrid is manufactured from extruded aluminium with a 3mm galvanized steel bottom plate and a reinforcement mesh in the cover. Tested to EN124 to pedestrian bearing, this recessed and locked manhole cover has three seals. There are two EPDM seals on the base and the third seal is a T rubber seal on the outside frame. The third seal reduces tension between the recessed cover and the frame, it prevents dirt building up and it contributes to the manhole cover being odour-proof and waterproof Please note: Manhole cover measurements are taken from the clear opening, the internal dimensions of the hole are taken to give the size manhole cover that is needed. This triple-sealed recessed manhole cover is 300mm x 300mm with a super shallow recess of 21mm and comes with specialist lifting keys provided by EcoGrid so that fitting and maintenance is easier. Triple-sealed aluminium recessed manhole covers are available from 150mm x 150mm to 1000mm x 1000mm in 21, 41mm and 61mm in-tray depths. EcoGrid Manhole Cover Specifications Clear opening/recess: 450mm x 450mm x 21mmExternal: 540mm x 540mm x 40mmLoading: Pedestrian