Threaded pipe plug gauges, also known as pipe thread plug gauges or pipe plugs, are used to check and inspect internal straight and tapered pipe threads. Straight pipe plug gauges are used to check straight pipe threads such as NPSM, NPSF, and BSPP thread types. Threaded Go gauges and No-Go plugs test if the internally threaded pipe is within tolerance by checking if the gauges mate cleanly with the threads. Tapered pipe thread plug gauges use L-1, L-3, and 6-Step gauges to perform similar tolerance checks. The L-1 and L-3 gauges are threaded, while the 6-Step is plain/smooth. An assembly includes a double-ended Taperlock handle with both Go and No-Go gauge members. All gauges are marked with nominal size and gauge type, and are right-handed unless stated otherwise.