I really love the concept of the Tonic Studio Pocket Shaker Creators as they do the job of fully sealing off all of the tiny, glittery shaker elements. I have tried both the 6x6 and 5x7 sizes. I love the wide seals that you will just need to peel off of the back on all four sides to secure the project. They really do hold everything in place.
The two reasons as to why I am not awarding 5 stars is that unlike other brands, these covers lack a protector film on both sides (neither side has one, I hunted for at least 10 minutes prior to realizing that they didn't exist. As a result, the cover didn't look as clear as other brands to which I have previously used. Secondly, I realized upon completion with both the 6x6 and 5x7 sizes that the finished project was actually slightly larger than the 6x6 and 5x7 card. It wasn't a problem for me with my 6x6 shaker as I had planned to use a 7x7 card base for the gift but with my 5x7 shaker, I needed to create a custom card base for the right fit.
I love shaker cards -- flat, stacked, and now pocket shaker cards. Just keep in mind that you might need a larger base for your card and that there is no protective film on the covers so handle with care.