These Plexiglass Round Jointers will make a nice clean slicked concave joint. Three great tools to have in your masonry tool box. The 1/4″ jointer is best for butterjoints (the smallest joint) because it will wear into the profile of the joint. These Plexiglass Jointers are specially tempered and eliminates “burn marks” on white mortar. “Burn Marks” are a discoloration from overworking the joint with metal tools. Simply wipe clean after use. Made in the USA!