We sell these cards because they’re really useful for recording things but have also found a lot of people look for them to design their own games. Other people have used them for school projects, as flash cards and for replacing lost or damaged cards from other games.
These gloss cards are blank on BOTH sides and (as you can probably see from the image) have a sheen and are slightly reflective. They are 56mm x 86mm in size (the typical size of most playing cards).
You can write on them with ball-point pens and Sharpie-type pens very easily, and the gloss coverage makes them durable. They are wipeable but please note that if you write on them with some wipeable pens (e.g. a whiteboard pen) they may still leave a faint stain on the card, even if you wipe the ink fairly quickly. We’ve tested this and it is really dependant on the pen you use; some whiteboard pens write on them OK and then are fully removable.