At Sun & Fun 2012 when talking with Andy it was pointed out that they engrave the fuel caps. Two more fuel caps were purchased with beautiful engraving saving having to use those ghastly stickers.
One of the old fuel caps will be kept in the aircraft to save the day when one comes off without permission... embarrassingly it has happened to me. Mine came off on the runway and was returned owing to the registration being engraved on it.
