Ever wondered what those numbers of rails of many airsoft guns mean and what are their purposes? Find out in the video from Orga Airsoft (in Japanese)... "I think that there are many Sabage players who are using Picatinny Rail to put dot sights and scopes on air guns. If you look closely at such a Picatinny rail, you can see a small number written in the groove, right? What is that number? Knowing this may change your consciousness when attaching accessories to an air gun."