I'm wondering if anyone can help me find an AR accessory I saw once, many years ago. It was a sort of thick plastic ruler that you could push into an AR15/M16 magazine to see how many rounds were loaded in the magazine without having to unload it one round at a time to count them. You'd push it down into the magazine until the follower bottomed out and you couldn't push it any further, then look at the corresponding number that was next to the magazine lips. That number would be the number of rounds in the mag. Make sense? Anyone know where these can be obtained? Some quick searching on Brownells and Midway didn't yield anything. Thanks.