The FAB Defense Gen-II Vertical Foregrip w/ Integrated Adjustable QR Bipod does not mount directly to M-LOK rail systems. You would need to use an M-LOK to picatinny adapter rail, like the one found by using the link below:
https://www.opticsplanet.com/leapers-utg-pro-m-lok-picatinny-rail-section-rejel.html?_iv_length=3-dot-14-in