Before starting a new motor, proper priming of the system is absolutely critical. These oil pump primers prohibit needless engine wear from improper lubrication upon initial start-up. These primers allow you to drive the oil pump with a 3/8 inch drill once the distributor is removed. The Chevy "Pro Model" not only primes the oil pump and bottom end but also the lifters and rocker assemblies. The "Pro Model" also has a top support that locks down with the distributor clamp to provide "hands free" operation. All are black oxide finished.