Crawler Innovations Lil Nova Micro Single Stage Foams are designed to improve the performance of your micro rig. Compatible with trucks like the ECX 1/24 Temper, 1/25 Proline Ambush, Losi Micro Crawler and other similar size and weight micro crawlers, these are a must have tuning option if you want to extract every bit of performance out of your little crawler. These foams will fit RC4WD micro tires as well! These foams are extra wide at 1.75" to provide for maximum tuning opportunity. Simply trim the width of the foams to soften the overall feel of the tire and sidewall stiffness. These are the medium density foams. Typically, you want to use a firmer foam in the rear than what you use in the front. This will help to prevent the truck from lifting the front end when climbing obstacles or steep grades. Additionally, the heavier the truck, the firmer insert you will want to use. Package includes two foams. Foams are also available in soft (CWR-2051) and firm (CWR-2053) densities.