Nylon Wing NutLightweight black nylon wing nut.  Lock-nut for the base of the Wind Instrument on the mounting rod — no tools required.  Handy for temporary mounting when daysailing. This is the metric M6 size, which is very hard to find in nylon.  It is not metal, so it is lightweight and non-magnetic, which is good near the digital compass in the tail of your Wind Instrument.