The Range-R Card is a passive distance finder made by Black Hills Design. It is used to determine distances using common objects, like the height of a man, a SUV, or a common field fence. It's made in the U.S. using a clear poly carbonate material. The easy to use device doesn't use batteries, or give off any electromagnetic emissions.
It weighs about an ounce and it seems pretty durable. The distance finder will fit in most pockets, and it does have attachment points for a lanyard. My only complaint is the distances on the distance finder card are indicated in meters. However there is a yard to meter conversion table etched into the card. I forgot to mention that everything on the card is laser etched, so it doesn't rub off. The card can be used in rain and snow. This device would be very useful in situations where batteries are in limited supply, since it doesn't use any power source. Overall, I'm happy with it, as it's a good investment during uncertain times.
https://www.blackhillsdesigns.net/product/range-r-card/