Six different US naval covers commemorating Operation Deep Freeze from 1971, 1972, and 1973, all unaddressed with Antarctic Treaty stamps (#1431) most with ship cancels. The covers have some handing wear, corner bumps, and age-related discoloration, and all but one are sealed.

USCGC Northwind 

McMurdo Station

USCGC Glacier

USCGC Burton Island

South Pole Station

US Naval Antarctic Support Activities (San Francisco cancel)

Most items under $20 ship in a first-class envelope with collectible stamps and with glassine and card stock for protection; more expensive or heavier items may go Ground Advantage or Priority Mail. 

Check out my store for stamps, postal stationery, and covers (first day, space, flight, and more) from the US and worldwide. Most items come from my historian dad’s collection amassed over the course of more than 65 years. He specialized in the US, Nepal, and mountain climbing but collected from all continents.