<https://humminbird.com.au/product/mounting-knobs-1100-series/#product>
<http://schema.org/description>
"OVERVIEW\nThe MKH 3 includes two gimbal knobs and rubber washers for 1100 Series models.\n\nCompatible with: all 1100 Series products.\nSet of two knobs\n1-Year Limited Warranty"
<https://humminbird.com.au/product/mounting-knobs-1100-series/>