Today I was going over some of my plans to work up loads for the new 300 WSM. The more I thought of it, the more I figured I should have a Chronograph. Sooooo, before I changed my mind I rushed off to the local gun shop and found them. Well, since I don't have much experience with them, it was kind of confusing looking at the boxes with different models and prices. Checked with the owner and he explained the difference in all the different models is the amount of memory. They all function the same. For my purposes all I needed was the F-1 Chrony. Grabbed it and out the door I went, after paying of course. Read the instructions and should do the trick. All I'll need is a note pad to make notes as I go along. Now if the weather would only smarten up I might get to use it. Might just have to set it up in the back yard and try some 177 pellets through it