Take quick, accurate window and door frame measurements with the CRL Accu-Rule Measuring Rod. Especially helpful for long or tall measurements, where common tape measures may bow or bend. The Accu-Rule is a two-piece heavy extruded aluminum telescoping slide with an accurate tape measure permanently affixed to the inner slide. What makes this tool exceptionally helpful for the window and door installer is the 3/8" thickness of the slide, which is thin enough to fit into most window and door frames. Both inner and outer slides are satin anodized to protect against corrosion, allowing the slide to operate freely for years. The larger size Cat. No. P8064 is an ideal tool for screen door installers.