Like the combination 3/4, 1/2, 3/8 inch combination Pocket Crimper, this tool works great. Use a large pair of vice grips to close the crimper around the crimp ring connection and the connection is sealed. All of my crimps passed the Go/No-Go Gauge test the first time. My connections were crimped over 12 months ago and have had 190+ degree F water flowing through them ever since with zero leaks...can't say the same for my buddy who opted for plastic compression fittings, but we replaced his with copper crimp rings and he's had no problems since. This tool is small so it works in the tight spaces where a lot of crimps are needed as well as easily stores in a tool box.