A square recess drive with a slight taper that wedges the bit, so the screw stays on the driver without being held. Sizes are coded by handle color: #0 yellow, #1 green, #2 red and #3 black, with red the everyday size for deck and wood screws. It resists cam-out well and is the default drive across Canada, while elsewhere it is mostly sold simply as square drive.
Heard on the job
Hand me the red Robertson, these deck screws are all number two square.
Also heard as
- square drive
Related terms
Phillips
A cross-shaped recess drive with tapered walls, the default drive on sheet metal, wood and small machine screws.
Torx
A six-lobed star drive that transmits more torque with less cam-out than cross or hex recesses.
Cam-out
The driver bit climbing out of a screw recess under torque, chewing up the recess and wearing the bit.