"MSD 8985 Timing Tapes for Harmonic Balancers Proper timing can mean the difference between winning and losing a race or even blowing an engine. The MSD timing tapes come with eight different sizes to fit common balancers ranging from 5.25"" to 8"" in diameter. The tapes are marked off in one degree increments from 14 degrees ATDC to 64 degrees BTDC and are printed on a tough, chemical resistant material. Not only do the MSD timing tapes help you get an exact timing setting, they allow you to see exactly where the total timing is set because total timing is just as critical as the initial timing."