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 semi-square body compresses and holds against the walls of a pre-drilled1/8 hole. For carbide or masonry drill bits used to drill the3/16 holes for these fasteners, see our No. 2243/16 Solid Carbide Drill with No. 2263/16 Hexagon Adaptor. Fastener dimensions:3/16 dia. x7/8 long. Hole size:3/16 x 1.