Amazon.com: J Hooks for Power Rack 3x3 J Cups for Squat Rack with Nylon Anti-Slip Pad 0.39Inch Thick Solid Steel -1500lbs Capacity for Weightlifting, Strength Training Power Cage Attachment (3''*3'' PIN 1'') :
X3M Magnetic Squat Rack Pins Review : Power Rack Attachments