Explore Scientific 5x Focal Extender1.25in Barrel. 25in Barrel 5x Focal Extender. The Explore Scientific 1.25in O.D. Barrel 5x Focal Extender offers generous eye relief and is especially great for eyeglass wearers. The Explore Scientific 1.25" Barrel 5x Focal Extender adds some real versatility to your telescope and really pushes for high magnification. Specifications for Explore Scientific 1.25in O.D. Barrel 5x Focal Extender: Barrel Size: 1.25" Length: 96mm Width: 45mm Weight: 260 grams; 9.2 oz Package Contents: Explore Scientific 1.25in Barrel 5x Focal Extender 5x Focal Extender; 1.25-inch O.D. Fully EMD-Coated on all air-to-air lens surfaces with all lens elements edge-blackened