These solid aluminum nails can be hammered into pre-drilled holes to fasten tackless strip or metal moldings down onto concrete subfloors, or onto tile or stone when necessary. The oval head of the No. 078 seats in metal moldings with countersunk holes. The semi-square body compresses and holds against the walls of a pre-drilled 1/8" hole. For carbide or masonry drill bits used to drill the 1/8" holes for these fasteners, see our No. 223 1/8" Solid Carbide Drill with No. 225 1/8" Hexagon Adaptor. Fastener dimensions: 1/8" dia. x 7/8" long. Hole size: 1/8" x 7/8“.