These adjustable extension tubes have male 42mm T-threads on one side, female 42mm

T-threads on the other side. With knurled locking ring. Center opening is 38.7mm or 1.53"

and the interior is grooved for light baffling. Black anodized aluminum, M42x0.75 threads.

For precision adjustment of astrophotography configurations.

Extension range is 31 to 48mm.

Price includes USPS Shipping in the USA!