KMC Character Guard Mat and Clear Standard Oversized Card Sleeves [10 Packs]

The answer is KMC. I learned about KMC while visiting Japan and seeing the selection of sleeves that they sell. Fortunately, I found the products online (Amazon usa). I'm not so certain you may find them in stock where you live, but give it a try. I personally got a pack of 10 KMC outer sleeves that end up costing about $4.4 each. https://a.co/d/0fhZdq6M Ever since, I have purchase even more KMC outer sleeves. I have at least 20 decks (standard + GLC) double sleeved. A lot of KMC, some dragon shield, some Kotamula.