Although ordered to the correct size, the helmet pressed so on jaw and cheek area that closing the mouth while wearing is not convenient. Otherwise it locates. And during a fight the restriction (though not therefore I use the helmet for boxing, but as protection against training weapons made of wood. From a different sport.) Falls anyway hardly noticeable.
The grid looks as if it would agree to (with good holding Velcro straps attached to the actual HLEM), but what I have not yet tried.
There is no real adjustment, but this has so far (with the exception of slight pressure on the jaw area) not bother me.
Conclusion: good helmet for the price. Whether it withstands a hitzigeren fight, or many hard hits, but I can not judge.