The gap between door and wall is 16mm(16/25") based on door thickness 40mm(1 4/7"). Door panel need to be cut a groove for floor guide, groove height:1"width:3/10". Two rollers can bear max weight 90kg.
8ft is 1pcs track(can work with 16 studs wall), . 10ft-16ft are combined tracks(not suitable for 16 studs wall). This item is made of steel and pom.