Economical collimation tool ensures that your reflector telescope's optics are in precise alignment. Combination 5inch long sight tube and 1.25inch Cheshire eyepiece. For aligning optics of Newtonian reflectors, Peephole in top and crosshairs at bottom enable precise optical centering. Compatible with 1.25inch telescope focusers or 2inch focusers with a step-down adapter for using 1.25inch accessories Size: 4.2*4.2*15.2cm Colour: Black Material: aluminum alloy Package Content: 1* Long Calibration Eyepiece 1* opp bag 1* box Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.