The L1 when screwed onto the pipe or plug
into the hole "hand tight" should be flush with the end of the pipe or the hole, or gage plane, within 1 turn.
L2 & L3 Pipe Gages
After using the L-1 gage the L2 ring or L3 plug is assembled with the part and must stop within 1/2 turn plus or minus of where the L1 stopped.