No bull, the only proven rail. - Daniel Defense M4A1 FSP Rail Interface System RIS II

There is nothing wrong with other manufactures rails. Buy what you like. The truth is these DD M4 and MK18 rails earned their reputation on the battlefield. They are heavy, bulky and the mounting system is “old” by todays standards. But the mounting system works. Dropped off the back of a 7 ton, or used to open a stuck latch on an AAV your weapon will still hold acceptable battlefield zero. Or just pick one up for a clone. Stop complaining it is “heavy” go to the gym…