Depends on the size of the photo or item you're sending. You want it to be just bigger than the item, but not too big where it will get folded.
Space enthusiast w/a Sharpie! Ex-journalist. Published in British Interplanetary Society's Spaceflight and National Geographic Traveler magazines; also NASA's Scientist-Astronauts, Freedom 7: The Historic Flight of Alan B. Shepard books and contributor to The Star Trek Encyclopedia: A Reference Guide to the Future and the A Matter of Time: The Unauthorized Back to the Future Lexicon among others. Follow me at @HBSastrowardoyo, check out my astronaut and other space travelers autograph collection at https://www.flickr.com/photos/45855752@ ... 973452526/