We have severial kinds of Stud welding gun to suits for different welding range, from M3-M25 differently. 

For stud range 3-25 mm, we have two types, one is Drawn Arc stud welding gun of 25-I, another is Drawn -25-II. 

The forma one could have same function with Nelson 20HD heavy duty gun, another could compatile with Koster-Co stud welding machine. More details, kindly contact with me. 

Stud Range(mm): 3~25 
Adjustable Hydraulic Damper: Option 
Adjustable Lift Assemble: Option 
Lift Setting(mm): 1~6 
Lift Coil Voltage(V): 25~70 
Control Cable Port: 4 
Control Cable: 4x1.0mm2 
Weight(kg): 2.7