Ấp Bắc Decoration.

[Taz]

This medal is classed as a special unit medal, cast in honour of the 261st National Liberation Front Battalion, besides the badge and official unit "honour" flag.(Not the flag shown above, it is satin and much more ornate)
Because all the recipients in 1963 were NLF personnel the medal does not remain included as an official SRV award.
The correct suspension has not yet been determined, seen on various coloured pentagonal suspension ribbons of the time period, metal suspensions (as shown below) and ribbon suspensions.
The stylized gold star is inscribed Ap Bac 2.1.1963 and shows on the left side a burning helicopter and APC, on the right the profiles of a male and female VC fighter the same as the badge.
The badge is coloured, the medal isn't, or should not be which makes the shown example strange, vet painted, dealer painted, it is impossible to tell. Both medals shown in Ed's book are the plain gilted style.