This Estella blade guard tie rod 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 secures the blade ring assembly in place. If your original blade guard tie rod knob is worn out or broken, replace it promptly to continue proper operation of your meat slicer.