A review for Sample Pack by Ikmal Ezzani.
If you are looking for highest quality stickers, you found it.
The stickers is thick, soft and slight rubbery. By touch, you know that it's waterproof as the texture feels like it. The stickers is thick enough to have a weight (hold on one side).
Only downside is, in one of the samples I've received; the colors of the design and the borders are blended in (white is not really white).
The samples really explains the StickerMule prints capability. Definitely a material that I'm looking for.