About Skin Zipper Air Hammer Driver Door Skinning Tool 1. Step One allows the technician to form the edge of the door skin to an initial 45 degree angle by holding the tool at a right angle to the door. No hammer and dolly work required here. 2. Step Two allows the technician to complete the final form by using the tool at a 45 degree angle. Two side slot widths are included for thick or thin sheet metal skins. When completed minimal finishing may be required on the corners and body lines. Skin Zipper reduces technician arm fatigue from hammer and dolly method as well as door refinishing time. The head will skin approximately 10 door skins and is easy to replace when it wears out. Labor/Material Savings: Saves the technician arm fatigue and up to 60 minutes of labor and assembly time by easily skinning the door with minimal refinish required to paint.