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The #19830 OPTEC-4300 to female Optec/DSI 3.5" threaded receiver allows any combination of our DSI 3.5-inch spacers to be easily installed on the camera side of the Gemini Focusing Rotator.

Inside Diameter: 3.5" DSI Thread
Outside Diameter: 4.95" (125.7mm)

Overall Height:

0.42" (10.7mm)
Clear Aperture: 3.46" (88mm)
Weight: 3.8 oz (110 g)
Back-Focus Usage: 0.1" (2.5mm)

The #19830 OPTEC-4300 to Optec/DSI 3.5" adapter converts the camera side receiver of the Gemini Focusing Rotator to a 3.5" x 24tpi receiver for the Optec/DSI 3.5" spacers.