I have the Colt original cheekriser that came with my Delta. It is a tension fit (two screws clamp it together.) There is no height adjustment whatsoever and the forward or back travel is very limited because it is moulded to fit over the buttstock.
It will only go so far forward before it brings up as a result of the tight fit with the taper on the stock as too much forward fit from the oem prescribed place would interfere with the charging handle anyways.
You can't slide it very far back either because then the tension system won't secure it enough., I would venture to say you have at most 2.5 inches of forward or aft adjustment. No more than that.
Not sure how the aftermarket ones work.
Hope this helps.
Regards,