The Combo B1 adapter kit from QHY is compatible with the QHY268M / 600, QHY CFW3L, and QHY OAG. It is also compatible with the QHY268M, QHY CFW3M-US, and QHY OAG. This kit will connect these devices to the 55mm BFL MPCC. Combo B1 is included as a standard accessory with both the QHY268M and QHY600 (short back focus version).
QHY took customer feedback and used it to create a fixed combination of adapter kits to meet the mainstream needs of most users. Since QHY offers so many adapters, there is a variety of back-focus distances that can be intimidating and confusing to new users. Users requested adapters that would provide 55mm of back focus, which is the perfect amount of back focus for astrophotography, in order to accommodate commonly available optical systems with field flatteners / correctors.
NOTE: If users do not have any special requirements for back focal length, you can use a standard T-mount. This kit is designed for those that need a specific back focal length to accommodate imaging accessories.
Below are a couple of diagrams that illustrate different configurations with the Combo B1.