The Semco Model 550 gun has been discontinued and replace with the Semco Model #250-20 and Model #250-32 guns.
The Semco® model 550 is designed for pneumatic application of sealant, caulking, adhesive and other compounds. Three versions of the Model 550 are available, one designed for 32 ounce cartridges, one designed for 20 cartridges and the another designed for 1/10 gallon cartridges.
Technical Data Sheet (pdf) on the Model 550 pneumatic gun
For more information about these products contact Bergdahl Associates, Inc.