The design of the tractors was the same as the Volvo T 24 and T 25, the next stage in the development of the T 20 family, but they were painted green. These were some of the improvements: increased engine power, wheelbase lengthened to 1 700 mm, bigger wheels, and better standard equipment, including hydraulic lift and power take-off.
The total weight was also increased slightly. The BM 24 was fitted with the Volvo CF 22, a 2,2 liter kerosene engine which developed 27,5 hk at 2 000 r/min. The BM 25 was fitted with the Volvo CB 22, a 2,2 liter gasoline engine which developed 31 hk at 2 000 r/min.