The ARMS SIR system was developed by the father of the M1913 “Picatinny” rail. It featured a free float aluminum and polymer handguard with customizable and removable M1913 rail sections that could be moved around based on the user’s preferences. I think they’re aesthetic asf and very functional. These were very forward thinking and saw a decent amount of use during the opening years of the GWOT before they were superseded by the cheese grater quad rails that just recently fell out of favor.