• The inside thumb turn should have a button to lock it and prevent its turning.

Tommy asked, closing the door behind him and engaging the thumb turn deadbolt.

Deadbolts have to be opened with a key or a thumb turn and offer good to excellent protection, depending on the quality.

This is a useful feature where the inside thumb turn can be reached through a broken or forced window, but it may contravene safety regulations.

Optional thumb turn or key lock.

The lock shall be a rim-mount, straight-throw springbolt type, having a live bolt retracted by thumb turn inside and by key outside and a brass cylinder with six pins.

See also Nightlatch Deadlock standard mortice lock, set into the edge of a door, with a square-ended bolt operated by key or, occasionally, by a thumb turn on the inside.

CHAPTER XI THUMBS TURN DOWN MARCUS BELD was uneasy.