This is an optional Kyosho 93mm HD Rear Universal Swing Shaft Set, and is intended for use with the Kyosho Inferno TKI3 1/8 scale buggy, as well as previous MP9 models. These driveshafts now have 3.5mm thick shafts, making them thicker and more durable than the original lightweight driveshafts that were included in the TKI2 kits. These are used in the rear position, and are recommended when using the wide rear track setup with 2mm offset hubs.