More accurate and easier to use than homemade wood preacher blocks. Adjustable for precise 5", 6", 7", or 8" exposures. Gauging block easily snaps into desired exposure position without use of tools or fasteners. Easily held with 1 hand while steadying new plank for nailing. May be used with overlap gauge for 1-person application. Tough, long-lasting, weather-resistant nylon material throughout.