The System 99 “Head unit” utilizes a stationary block in which the main pulley is mounted on a 4.75″ by 8.5″ by 3/8″ thick aircraft aluminum backing plate. The head unit weighs 3.5 pounds and provides 360 degree portability. It is so flexible it allows the user to move at any angle and in any direction. The large pulley on the head unit on the System *99* is a friction brake head block assembly that consists of a 3.5″ diameter by 2″ deep aircraft aluminum capstan roller drum. Made in the U.S.A.