FeaturesFlat sides provide excellent contact for locknutsExternal ears are used to nail the ring to the wood formTop cover is removable for before-pour workWaxed fixture ears prevent concrete from interfering with the threadsEars on inside of box are for fixturesSupport a light fixture up to 50 lbSingle row side knockoutsCover plate must be ordered separately with all (except 280 which includes a 891 cover)