Our brand new heavy-duty billet flywheels are fully CNC machined from high quality 1045 super hard billet steel. The ring gear is made from high manganese carbon steel for accuracy and superior wear resistance. Ring gear is 130 tooth, weight is 27 pounds, and the overall diameter is 13.19 inches. The diameter of the machined face (without the ring gear) is about 12.5 inches. These fit a standard six bolt crank flange. The larger of the two bolt patterns measures 11 5/8" across (bolt hole center to center) and has 6 bolts evenly spaced around the outside of the wheel. These are very similar to the Mopar Performance part# P4529142 and McLeod #464102. Fits ALL Mopar V8 engines (even small blocks!) Works with 10.5 inch clutch only. These can be used for either internal or external balance applications. They include a small weight which is bolted to the back of the flywheel. For internal balance applications, simply remove this bolt-on weight. For external balance applications, when the engine is being balanced with the flywheel attached, your balance shop can remove material from the supplied bolt-on weight as needed to bring the engine into balance. For factory pre-balanced applications such as cast crank, six pack, etc, Brewers performance carries specific external weights for these applications, available HERE