If you are a long-range shooter you'll want to check out this piece of gear. The Accurate Shooter has the details:
"If you often shoot at multiple distances, it’s smart to keep a come-up table (ballistics chart) with your gun. Some guys have a laminated card, while others print out a ballistics chart and tape that to their buttstock. That works, but it’s not a very stylish solution.
Leupold sells a cool, compact Retractable Ballistics Chart that holds your ballistics data on a retractable tape in a plastic housing. Write your come-ups on the tape with a permanent marker pen, such as a fine-point Sharpie. Access the data just like using a measuring tape — pull out to read and then the tape rolls back into the housing. This black plastic, scope-mounted device retails for about $35.00. There are two different versions — part #54804 for 1″-diameter scope tubes and part #54778 for 30mm scopes."I have never been very good shooting at extended distances (>500 meters), but I would like to learn and improve that skill set someday. Until then, critters within rock throwing range better watch out!
H/T: Accurate Shooter