The Cushcore 27.5+ Set is an engineered foam insert that mounts inside a mountain bike tyre.  It divides the inner volume of the tyre in half, with air underneath the tread and the CushCore insert next to the rim. The purpose of Cushcore is to improve the ride quality of your bike.  It is not just for flat protection.  CushCore absorbs shock, stops deflection off obstacles, reduces vibration, and stabilizes the tyre against roll and squirm.  Think of it as suspension for your tyres designed to give you a faster, smoother ride. Cushcore 27.5+ Set Features 2 CushCore Inserts 2 CushCore Tubeless Air Valves Rim Stickers Installation Instructions Cushcore 27.5+ Set Compatability CushCore is compatible with your current tubeless tyres and rims Fits tyre widths 2.1 - 2.6 Fits rims with internal width 22 - 35mm If your wheels are not tubeless ready, rim sealing tape will be required We recommend the use of tubeless tyre sealant with CushCore Installation with certain tyre & wheel combinations may require two people - one to work the tyre levers, and another to hold the tyre bead in the drop center of the rim.  Wire bead downhill tyres are most likely to need extra help.   CushCore inserts are extremely durable.  Our foam is engineered to withstand repeated pounding and flexing without degradation.  It does not absorb liquid and is not affected by tyre sealant.  Service life will depend on your riding frequency, terrain, etc.  installation with certain tire & wheel combinations may require two people - one to work the tire levers, and another to hold the tire bead in the drop center of the rim. Wire bead downhill tires are most likely to need extra help.