5mm 長 48mm 延長管 (SFE-M48-005)

I was chasing just a few more millimeters of back focus and this 5mm tube did the trick. The male thread is short enough that it doesn't bottom out, and the 4.6mm deep female side grabs solidly.

Threads on this fit my 2" focuser perfectly and the 4.6mm deep female side gives plenty of bite so nothing wobbles. Needed exactly 5mm to hit focus with my reducer and this did the trick without adding any flex.

Screwed this onto my imaging train to hit the exact 55mm backfocus and the threads mated cleanly with no wobble. The 5mm it adds was precisely what I needed to get my field flattener spacing right. Solid little tube, does exactly what it says.