●Reflector telescope universal focuser adapter applies to accessories with M42x0.75 thread and can also be applied to 1.25" eyepieces. Optical path length: 1.5 - 1.8 inches (37 - 45 ●Equipped with 3 locking thumb screws to secure inserted 1.25" celestial accessories. Comes with a ring to secure the focuser ●Metal construction and anodized aluminum surface treatment, durable for long time use ●EASY TO USE: The universal reflector telescope focus adapter is easy to handle. Turn the three screws to fine tune the eyepiece to fit the object ●Equipped with brass side clamping screws to prevent accidental slippage and keep your telescope safe