Save up to 3 profitable hours on each job with the innovative Sider. It works quickly and accurately, replacing chalk lines, squares and straight edges. Use it as a scribe or square to mark or score precise lines. Or go straight to cutting with your utility knife in the precisely marked 1/8" (3.2 mm) holes. The Sider comes in 5 sizes to match popular siding profiles and features durable 18-gauge (1.22 mm) stainless steel construction. It's one smart little tool for even the biggest siding jobs.