This CA-35 is a 2" nose to M54 61mm extension. The Takahashi M54 to T2 adapter then allows you to connect T2 adapters to it. For me this works really well on my FSQ-85. I've got a 2" Baader Clicklock it (as I do all my scopes). So I can easily attach a 2" diagonal for visual and then quickly swap out an image train with this attached to get me right in the sweet spot for my FSQ-85's backfocus. An alternative would be a combination of T2 extensions and a Baader 2" nose to T2 adapter which I also have and use on other scopes but again for my setup this is all I need with my Clicklock and 55mm image train to get me right in the middle of my focuser on the FSQ-85. Solid bit of kit.