Specially designed for securing all types of metal trim and tackless strip. Works equally well in cement, terrazzo, marble, slate or any masonry floor. The four corners of the square drive contact the wall of the undersize round hole with tremendous force—generating several times more holding power than is necessary for secure fastening. Available in six popular sizes in either 1 lb. jars, or economical 25 lb. bulk boxes.
Flat head style is: 3/16" diameter x 1-1/8" long and requires a 3/16" x 1-1/4" hole.