These tools are used to remove air bubbles and squeezing the GRP laminate into an integral structure. The use of these metal rollers also reduces unnecessary over wetting of the laminate which saves money and time. Rollers are supplied in various shapes all attached to a steel spindle with high grade plastic handles similar to decorating handles but all do the same job. Most rollers will accept an extension handle. Must be cleaned in acetone before the resin hardens. A useful and necessary tool.