Marples Trial 1 range is made from designs produced over 70 years ago. The Trial 1 range features some of the highest quality specifications expected in these measuring and marking tools. The squares are made from walnut and have 1/8th inch thick machined brass on both the inside and outside faces, thus ensuring accuracy on the inside and outside edges. They have a chemically blacked spring steel blade, secured to the stock with brass diamond washers and steel rivets.