This Pack Contains 2 x Top Plate Fitting Braked Castors + 2 x Swivel Castors | Heavy Duty 8 Range Castors are designed using a different bearing configuration and much thicker steel to enable their higher carrying capability. Heavy Duty 8 Range castors also benefit from a maintenance grease nipple. The wheel used has a polyurethane tyre which will offer smooth running over a compact floor. This is a very strong durable product and extremely common for all heavy-duty castor applications. Not sure please call our technical team before purchasing 0044 1296 431135