These Hipshot A Style Bridges feature Graphtech Ghost saddles. These can be used in combination with magnetic pickups or without. The piezo version of the A style bridge is generally the same, with the exception of a slot in the bass plate for the piezo wire to pass through as well as a differently styled saddle. A buffer is used to get the piezo signal to the correct level.
Hipshot A Style Bass bridges are available in a wide variety of string spacing; in your choice of aluminum or brass. Type A bridges feature variable string spacing adjustment and thru the body option for even greater versatility and fine intonation adjustment as well. 17mm = .669" 18mm = .708" 18.24mm = .718" 19mm = .750" 20mm = .787"