I love the Staples Heavy Weight Sheet Protectors because of thickness clear see through and I bought 2 packs and got a deal on the second. The less thick ones often fold on themselves. I recommend these for valued memories.
Over the last few years I have used Staples Sheet Protectors for protecting various documents. Some documents were posted outside in the elements and on bulletin boards. The Sheet Protectors have always held up to the elements as expected.