This Estella stem locking knob is a direct replacement for the one that came standard on your Estella SL series meat slicer. It is compatible with SLM12, SLM13, SLA13, and SLA13S meat slicers. This knob securely fastens the hopper in place. If your original stem locking knob is worn out or broken, replace it promptly to continue proper operation of your meat slicer.