Common felt mats give a smooth contact between record and platter but have the disadvantage of static build-up and excessive 'slip'. That means that felt mats often collect a lot of dust, which can be then transferred to the record. Also the damping ability is very limited, which can be a problem with metal platters. Thick rubber mats over damp the record and have an isolation effect, which leaves static build-up on the record so you can still hear noisy clicks and pops. Leather is an ideal alternative material, reducing static, minimising slip and absorbing resonances before they get to the record.