This small 35mm extender Kepler is especially useful to help you achieve focus on instruments equipped with a 31.75mm eyepiece holder. You can use this extra 35mm to focus when the focuser stroke is over (especially on lenses with a very far focus). It is equipped with a knurled screw ring clamp, which provides uniform locking around the circumference of the accessories and does not mark the barrels.
It is equipped with a safety slot and thread to receive 1.25", 31.75 mm mounted filters.