Sig sauer m 400 tread

[USMC87]

My sister in law just bought a Sig m 400 10" pistol with sig hand guard m lok, The salesman told her that only sig parts would work on the hand guard. I am not very familiar with the topic so I am asking you guys if regular m lok accessories will work on the hand guard? Thanks a lot for any help.

[monadnock#5]

I have a SIG MCX. The forend takes the regular M-lok attachments.

[USMC87]

Thank you sir!