1-Gang BLOCK-LOC® Masonry Box, Gangable, 3-1/2 in. Deep, Conduit KO's. Integral brackets securely hold box to concrete block from front and back in masonry block walls, even in irregular openings. Gangable masonry boxes offer the option of constructing a box to hold two or more devices. TKO® Knockouts allow for design and installation flexibility. Supplied with ten 1/2-3/4 in. TKO® knockouts. Quick and accurate positioning. 22.5 cu. in. capacity.