Dual Head Straight Foot Service Gauge for Inner Duals. Milton® precision engineered service gauges provide accurate, long life and trouble free performance. Plated brass tube and 4 sided nylon indicator bar. Service Gauge Straight foot dual head chuck is 13 1/4" length. PSI range is 10 PSI to 160 PSI, in 2 lb. increments; 80 to 1100 kPa in 20 kPa increments.