Leupold Retractable Drop Chart Thingy
Just saw one of these on a scope - I like it. Well made, simple and does not take up much room on the scope tube. Puts the numbers right in front of you, no looking for a chart on the side of your rifle or where-ever. Pull out tape is 10 inches long and 1/2 inch wide, lots of room for data. You simply write on one side with a pen, (side has a special white paint), can be cleaned off to re-use if you change loads.
Also put the ACI device on and can tell you that it is one well-built, precision tool. Hope to shoot with it in some very steep coullees we hunt. Also does not take up much room, no sweat to get to the turrets on the NXS.
By the time a person mounted an ACI, the Retractable Chart and a ScopeLevel, the scope would look pretty busy...