Punctures are a memory. The SmartGuard® layer made from a flexible, special rubber offers particular resistance to shards of glass and flints. Even a thumbtack cannot penetrate this protective layer. The SmartGuard belt does not increase rolling resistance. The MARATHON PLUS rolls as easily as a tire without protection. It is impossible to guarantee that a flat will never happen, but the Marathon Plus has the best defense against everyday tire wreckers such as glass, flints or metal shards. Use a pressure gauge to adjust tire pressures as the common 'thumb check' is insufficient due to the special construction of the Marathon Plus.