Yes they say the measurements of the threads outside or major of the thread 16.6 16.7 which is the hm1000 reg they got labeled and 19 mm hm1000x I just ordered one for my hm1000x my major of my threads were 16.5 but my hm1000x is older so I ordered the hm1000 reg from huma my s/n starts with hm also and the newer hm1000x s/n starts I guess with hmx so I hope I got the right one coming