With all the recent discussion on here about swarm trap size, I decided to measure mine up. I am running double 5 frame medium nucs for swarm traps. The inside dimensions are 6.625"x8.25"x18.25" for a total of 997.47 cubic inches, for a single 5 frame nuc. Doubled up that is 1994.94 cubic inches.
I have heard that the European Honey Bee likes a cavity between 30-40 cubic liters. My double 5 frame medium nucs come in at 32.74 cubic liters.
I havent seen anyone claiming to be using double 5 frame medium nucs, but it seems that I have hit the target goal for cavity size.