I've had this tool for about 6 hours now and it has payed for itself.  It saves your hands not to mention time and material.  The specific caulk we use this on has a tenancy to leak bout the back of the tube into the barrel of the calking gun and jam everything up.  With the caulk master it uses air pressure to push out the material so none leaks out the back.  This thing is great and I wish I had it months ago when i started this job.