For the stroller. With extra-safe puncture protection (Puncture Guard). The special tread compound Black'n Roll leaves no black marks on the floor. Active Line: The framework of all Active Line tires is made from high-quality 50 EPI carcass. Coarse 20 or 24 EPI carcasses are no longer available from Schwalbe. Black'n Roll: Special rubber mixture for wheelchair tires. Leaves no dark marks on gym floors. Lasts significantly longer than a gray wheelchair compound. TwinSkin: An additional rubber coating on the side protects against cuts and allows for uniform coloring. Puncture Guard: The Puncture Guard in Road Plus is about 3 mm thick, but not as highly elastic as a Smart or Green Guard. The classic center rib profile offers pleasant rolling characteristics.