this is a great system for sound for electric planes it come with mother board which is the small green board an has an amp extension which is the larger black board the system will work with out the amp black board its just needed to power 2 extra 4oh speackers whole system was over 300$ works great has start up sound of a b-25 an can have more engine sounds at there web sight you down load on the flash driver included an also has machine gun sounds down loaded already in it 4 speakers mother board amp board an this thing is loud asking 150 will be at newark ohio swap meet if not sold on the 2nd of feb will work off 3- 6 cell lypos batteries great sound great price
