Total Seal leak down testers have a superior dual-gauge design. They're an adjustable left hand gauge, with a precision regulator and a large easy-to-read right hand gauge. Gauge reads from 0 to 100 in increments of one PSI for precision settings.
This tool comes with a 14mm spark plug hose and allows you to check engine condition. With an adapter they can also be used to set injection barrel valves.
Buyer will need to provide air chuck fitting to install to their air hose system. Gauges are 2.50" in diameter and hose is eighteen inches long to get down into Hemi cylinder heads.
Simply plug the leak down gauge into your air supply, set the gauge to a hundred PSI and set the leak down on the barrel valve with the other gauge or check cylinder leakage cylinder by cylinder.