The "MS" compound is firmer than the stock foam donuts

allows driver to vary stiffness for track conditions

Includes both the rear chassis plate (rear bulkhead) and arm mount

They moved the entire skid plate from between the chassis plate and differential to below the aluminum chassis plate

4GHz radio technology to give you trouble-free and total control of your RC car

HPI Racing - Dirt Buster Block Tire, M Compound, 170x60mm, (2pcs), Baja 5B ASC80950 The "MS" compound is firmerPerfect for racing on rough and grassy surfaces, these front square block pattern tyres for the Baja are what every Baja racer has been begging for! Great in long and short grass conditions and designed by the HPI R&D team, you don't have to look any further for amazing front end traction!