Thread Restrict or pitch diameter Restrict is a regular useful for classifying the tolerance in the thread pitch diameter for faucets. For imperial, H or L limits are used which designate the amount of models of 0.0005 inch more than or undersized the pitch diameter is from its primary value, https://types-of-shingle49258.ltfblog.com/28756818/details-fiction-and-types-of-screw-head-drives