This is a Mauritius Censor Cover from 1944.  it was sent from Port Louis via Railway to the US.

In addition to the censor tape, this cover has a usage of a pair of SG 256 and 256a, the 10 Cents Red.  The left stamp is 256a, and has the SLICED S ERROR.  These are valued at L40 in the Stanley Gibbons Catalogue when off cover.

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!