Of Rexroth ZDB/Z2DB6 4X series stacking relief 
 1, the stacking structure 
 2, the mounting surface to DIN 24.34 thousand, Type A 
 3, 4 pressure level 
 4, 5, effective flow of darkness can be optional 
 5, with one or two plug-in relief valve 
 6, four kinds of adjustment in the form 
 The ① adjustment handle ② with hexagon nut and protective cap screws (3) with a scale can be lock knob (4) Rotary knob with scale 
 http://www.jnlsl.cn/showproduct.asp?big=1&small=2&list=8&proid=24