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Amazon.com: Space Shuttle Challenger $3.00 Priority Mail Postage Stamp Scott 2544 by US Postal Service : Toys & Games
![Hi! Will someone help me understand how to buy postage for the flat rate envelopes with the clear window (EP14H, 10"x5"). The "How to Use" instructions are confusing to me...and the website Hi! Will someone help me understand how to buy postage for the flat rate envelopes with the clear window (EP14H, 10"x5"). The "How to Use" instructions are confusing to me...and the website](https://preview.redd.it/t85916r2dn661.jpg?auto=webp&s=aa0baf518939d59947ade6cfd95dd87b7e1785cf)
Hi! Will someone help me understand how to buy postage for the flat rate envelopes with the clear window (EP14H, 10"x5"). The "How to Use" instructions are confusing to me...and the website
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