The flex-shaft BP25H back-pack vibrator allows contractors to carry the unit around a jobsite without dragging electrical cords. Powered by a 2.5-hp Honda gas engine, the unit weighs only 24 pounds. It is offered with 11 heads — seven steel and four rubber — that range in diameter from 7/8 to 23/4 inches with a maximum length of 173/4 inches. Flexible shafts are from 2 to 21 feet long.