What are wafer seals used for?
Wafer seals are round, transparent stickers. There's a variety of reasons to use wafer seals, but they are most often used for sealing envelopes, pamphlets or boxes that are going to be mailed.
Some companies send their products out in personalized boxes or envelopes which usually have some kind of design and color theme. Pamphlets usually have images or a logo on the outside that's advertising their company or product.
What size wafer seal should I use?
If you're sealing something small like a pamphlet or envelope, the 3/4" or 1" dot is a great solution.
If you're sealing a larger box, package or envelope, then the 1" dot probably won't be large enough to secure it properly. Using a 2" or 3" seal will provide more adhesive to keep the package securely sealed.
Using a clear seal instead of a colored dot gives you the option to seal a pamphlet or package without covering up the design. If a company has spent the money and gone through the time and effort of printing a design on their packaging, it would be a shame to cover it up with colored dot. A clear seal will provide adhesive and also keep the images or colors visible.