The problem with cast iron blocks is not so much the squealing when braking, but more the rumble of the rolling noise, caused by metal wear debris particles becoming welded onto the wheel.
The K-block material, produced using plastic composite technology, leaves no material deposits on the running surface of the wheel, thus preventing a rumbling noise.
The noise levels of wheels braked using K-blocks are reduced by up to 8 dB(A), slashing perceived rolling noise by half.