Mounting Knob - Black ABS Plastic - SingleDimensions35mm diameter by 15mm thick, not including shaft which is 4mm diameter by 10mm longFits Standard Horizon modelsGX1000S Eclipse or GX1300S Eclipse. GX1600 Explorer or GX1700 Explorer GPS. GX2000 Matrix, GX2100 Matrix AIS, GX2150 Matrix AIS and GX2200 Matrix AIS/GPS. GX2400B Matrix AIS/GPS. GX6000