This is an Antigua 1941 OHMS Cover, sent to Los Angeles by Air Mail on 8/5/1941.  

What makes this guy special is that it was countersigned by the initials at its lower left.  It was also sent with Mixed Colony Franking in the form of Antigua KGVI SG 99, the 1d, along with a pair of Leeward Islands KGVI SG 105a, the 2 1/2d light bright blue.