The cheek rest does not adjust. You would either need to add a riser, or replace the stock with a model that has an adjustable cheek rest.
The entire extension tube and stock assembly have an inch of vertical adjustment. The tube is retained in a vertical dovetail, and the tube can be positioned and clamped anywhere in that one inch of travel. The overall cheek weld height is adjustable. This adapter comes with the VLTOR Emod stock, but will accept any mil-spec AR/M4 buttstock. You could theoretically adjust cheek weld height further by using a different mil-spec pattern stock that had different cheek weld accommodations.