Perspective IR sunglasses is a good device which can help poker player read back marked deck cards safely and clearly.
This perspective sunglasses are processed by regular good quality sunglasses. From their appearances, it is hard to notice any secret of it. IR sunglasses can be used under any light, and white light is the best. When you wear this infrared sunglasses in marked cards games, you can see the invisible ink markings on the backsides of each piece of marked deck.
Due to the perfect procession, others around you cannot find any secret of it and  will not cause any attention of other players.