28-1a, Eaton's Motor Machine Gun Battery Cap Badge, Crossed Guns
2 lugs
Gaunt maker's tablet.
(4) Solder reinforcing spots on the reverse.
This appears on page 91 of Charlton and on page 49 in Rosen, listed as 31-4a and correctly described as "Rare" but seems out of sequence so am going with Charlton's description and have therefore numbered 28-1a.