The Ruwac Duo-Vac 220-S vacuum system combines two 220-V, 4-hp vacuums with a proprietary 3-in. inlet to create the power, suction strength, and impact resistance to collect the dust from shot blasting, grinding, and polishing operations. The Vacuum-On-Demand feature controls the quantity of cfm with individual motor control switch gears. Contractors with two ongoing jobs can disconnect the units without tools and transport them to different locations. These vacuums accommodate grinders up to 44 in. in size or four 7-in. hand grinders. Aramsco Inc. 800-767-6933.