This is a Grenada OHMS, or ON HIS MAJESTY'S SERVICE Registered Cover.  It was sent from St. George's to Newark, New Jersey on 4/24/1902

What makes this little beauty really special is the numerous transit and receiver marks on the back, as well as the use of Grenada SGs 48-53, the 1/2d x 3, the 1d, the 2d x 2, and the 3d.  This totals 9 1/2d used for postage and registration fees.  These stamps are valued at L60 x 4 = L240 in the Stanley Gibbons Catalogue!  

The cover itself is in Very Fine condition.  This item is over $100 USD so I will ship it using Priority Mail in the US, and Registered Mail overseas.  This is to ensure that it reaches you in a safe and timely manner, and includes tracking!