They are offered to you with different source objects and different adjustment modes.
The collimators are designed to place a luminous object at infinity.
Focal length: 175 mm achromatic AR Focusing adjustment: knob and rack Outer diameter: 38 mm Effective diameter: 32 mm Adjustable reticle: cross or target (optional) Lighting: removable white LED Power supply: 6V DC with dimmer (included) Structure: lacquered aluminum Mounting: 10 mm rod - L130 mm Storage: plastic case