Mount accessories on your tripod fluid head with the ARRI 3/8"-16" Accessory Mounting Block from Miller. Compatible with ArtX, CX, and Compass heads, this block does not include the separately available bracket assembly (#12715). It attaches to either side of your fluid head and features three ARRI anti-twist 3/8"-16 threads, one 3/8"-16 thread, and one 1/4"-20 thread.