These timpani are ideal for small orchestras and bands to use in rehearsals. They are quite effective, though, of course, not as powerful as proper timpani. The tuning is effected by rotating the drum itself and the indices (note letters) come set, but can be reset easily. Though the heads of rototimps are 12" and 14", the pitch of the sound is the same as that of a 25" and 29" set of normal timpani. This sounds impossible but there is a good scientific reason why it is so!