HardTop coasters with a heat sensitive area which becomes transparent when hot revealing the printed image beneath. Due to nature of PVC material some distortion with heat can occur particularly if used with plastic vending-machine cups. If you think that this might be an issue, we are pleased to recommend our optional, higher heat resistant polycarbonate material. Please ask for samples and details of additional costs before deciding which coaster is most suitable for you. Prices based on 3mm thick coaster with 12cm2 of heat sensitive ink.