I ordered the linear hack squat machine about 3 weeks ago for my Physical Therapy clinic. I absolutely love the machine. The seat glides smoothly and the angle of the machine and seat do NOT put unnecessary stress on your knees and lower back like other leg press machines. My patients have commented that "it's a nice piece of equipment" My only complaint is with the assembly instructions and the installation of the spring for the lock arm mechanism. The directions provide no guidance on how to install the spring. In order to save yourself a lot of time and aggregravation, DO NOT install the seat to the guide rods before you install the spring to the seat and lock arm mechanism. If you install the seat to the guide rods as per the directions you will never be able to install the spring. For this reason, I'm rating this a 4 star. Otherwise the machine is a 5 star.