PROFORM's new on-head valve spring tester features a digital gauge and an adjustable base to fit all common aluminum rocker lengths and offsets. The digital gauge includes 5 lb (or 2 kg) increments with peak hold and backlighting features. The housing is made of black anodized billet aluminum with knurled grip area for ease of use. Capacity range from 0-600 lbs (or 273 kgs).