Image, Left Side ... you can see the large clear aperture of the adaptor.
Image, Right Side ... the adaptor offers a somewhat shorter optical length than normal - only the actual thickness of the T2 ring will remain.

T-2 is a common standard thread for many astronomical adaptations. This offers a great versatility because you can build an entire adaptor system around the T2 thread (see TS and Baader adaptor systems). However, T2 limits the possible field of view. A typical T2 adaptation has a clear aperture of about 38mm. This 2"-EOS special adaptation offers a clear aperture of 47mm!

In addition the adaptor is a little shorter than standard adaptations because only the actual thickness of the T-2 bayonet ring will remain.

Specifications:

-- 2" Adapter - direct adaptation from 2" to the EOS bayonet
-- with 2" filter thread at the lower end of the barrel
-- length of the 2" barrel: 30mm
-- effective optical length: Only 10mm
-- clear aperture: 47mm!!!