The TC-Series Clear Aluminum Insert Timpani drumheads feature bright, focused tonality with outstanding projection and sustain. Featuring a 7.5-mil Clear film combined with an Aluminum Insert ring for added tuning stability, sustain and projection, TC-Series Clear Aluminum Insert Timpani drumheads provide the greatest amount of sustain and projection of all Timpani drumheads, making them ideal for outdoor use, especially Marching applications. Available in sizes extended collar 22", 25", 28", 31" and 34". Other sizes 20" - 35" available by special order.