Rick Yandrick is an astrophotographer putting together a 10" f5 Newtonian Astrograph. He purchased a 12" carbon fiber sandwiched cored OTA tube and a custom carbon fiber mirror cell. 

   

Yoke style, carbon fiber mirror cell: 10" OD x 3.125" at the end sections x 1.15" thick: 193.1 grams/ 0.425 lbs.

This was a custom mirror cell with drawing provided from the customer.
 
   
   
 

   
 
   

The customer's mirror cell sitting on the back side of a 12.5" f4 conical primary.

Another view of the yoke cell along with the 12.5" conical primary.