Left hand nuts look like regular nuts but are threaded opposite of “standard” (right-hand) nuts. Consequently, turn them counterclockwise to install and tighten. Often abbreviated “LH” for left-hand, use left hand nuts with left hand threaded bolts, screws, studs and threaded rod. They are also known as: reverse threaded nuts.
Available in Metric M6 to M30
Imperial BSW :- 1/4″ to 1-1/2″
Other sizes available or order-able if required