It is an adapter, converts a 6SN7 octal to a 6F8 octal.  My supply of older tubes is limited and the 6F8 apparently is fairly expensive. The gray wire is a "Grid Cap" wire.
30 minute project and works great in my "Frankenstein" HRO receiver. Tip: When wiring up an adapter using leads of various lengths, feed them through the male octal pins and then trim.