Body-Solid GLPH1100 Leg Press/Hack Squat Machine Quad Track roller System operates smoothly and distributes weight evenly Both back pads utilize a quick flip-and-lock mechanism Extra-heavy Gauge diamond plate foot platforms for both leg press and hack squat positions Easy-access under-carriage plate load System Extra heavy-duty 2"x 4" 11-gauge steel mainframe minimizes torsional flex for maximum strength and stability