This .400 barb punch is used to punch the larger .400 x loc sleeve barbs into 1 inch or larger oval hose for higher flow requirements. Easy to use with its sharp metal tip. Punch the tip into the tubing and twist to cut a hole the correct size for the .400 barb to fit into. Can also be used to install the loc sleeve fitting at the same time by slipping the metal tip through the loc sleeve fitting so it fits out the end of the barb. This allows the tool to cut the hole and push the loc sleeve barb into the oval hose at the same time.