HPI Racing Molded Inner Foams are optional equipment for the front of the Baja 5T line of 1/5th scale trucks. These are moulded foam donuts that help support the tyre for stable performance. The "MS" compound is firmer than the stock foam donuts, giving the steering a precise feeling when making sharp steering transitions. Sold in pairs.#4804 INNER FOAM (SOFT/190x60mm/2pcs) (for front tyres)#4817 MOLDED INNER FOAM MS (190x60mm/2pcs) (for front tyres)#4818 MOLDED INNER FOAM MS (190x70mm/2pcs) (for rear tyres)