Tackless Strip
A thin wood strip with angled pins, nailed or glued around the perimeter to grip stretched carpet.
Tackless strip (sometimes called gripper strip) is the perimeter anchor for stretched broadloom carpet. It's a 1.25" wide thin wood strip with rows of upward-angled pins. Once nailed or glued to the subfloor around the room's perimeter, the carpet is power-stretched over the pins, which grip it permanently.
Tackless strip placement matters — too far from the wall leaves a gap, too close creates a hard ridge. Standard practice is to leave a gap equal to about 2/3 the carpet's pile height.
The pins are sharp. Always wear gloves when handling. Treat tackless strip as standard install material — it's cheap and you'll use it on every carpet job.