Economical collimation tool ensures precise alignment of your reflector telescope's optics. Combination 5-inch long sight tube and 1.25-inch Cheshire eyepiece. Designed for aligning optics of Newtonian reflectors. Peephole in top and crosshairs at bottom enable accurate optical centering. Compatible with 1.25-inch telescope focusers or 2-inch focusers using a step-down adapter for 1.25-inch accessories. Size: 4.2 x 4.2 x 15.2 cm Color: Black Material: Aluminum alloy Package Content: 1 x Long Calibration Eyepiece, 1 x OPP bag, 1 x box Only the above package content is included; other products are not included. Note: Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement may vary by +/- 1-3 cm.