Lumicon 2 Inch Easy Guider Attachment Ring - SCT MaleLumicon 2 Inch Easy Guider Attachment Ring SCT Male allows Lumicon's 2 Easy Guider to be used on Schmidt Cassegrain telescope's with standard SCT male (2 x 24 tpi) rear cells. Lumicon 2 Inch Easy Guider Attachment Ring SCT Male Lumicon 2 Inch Easy Guider Attachment Ring SCT Male allows Lumicon's 2 Easy Guider to be used on Schmidt Cassegrain telescope's with standard SCT male (2 x 24 tpi) rear cells. One set screw. Measurements: Full Length: 13. 2 mm