Got three of these for my A&K Masada, and I have to say, I'm impressed. They work as advertised, and are a very cheap (but viable) alternative to A&K's Masada CQB RIS conversion kit. They might be made out of plastic, but it is a very sturdy kind of plastic, so there's no worry about them getting broken. Moreover, they come with two ladder-style rail covers, allowing you to keep one on and still use the other half of the rail for whatever you want to attach to it.
There are some things that are keeping me from giving 5 stars, however. The rail covers are also made from a sturdy plastic: they'll keep your rails safe without a doubt, but they are downright impossible to get off while the rail is still on the gun. Also, they came slightly bowed inward. I only noticed this when I tried to put them on the gun, however, I don't think AirsoftGI (who does an admirable job at packing items) or UPS are at fault for this. If anything, the plastic probably warped because of the cold (one of the many perks of living up north...).
Either way, if you have a gun with an MOE-type handguard and don't want to spend the cash on expensive Magpul parts or rail conversion kits, then this is the way to go.
-multiple screw-in points
-sturdy plastic everywhere except the screws and back plates, which are metal
-ladder-style rail covers included
-rail covers are impossible to get off while the rail is on the gun.
-rails came slightly bent (not AirsoftGI's fault, problem with the cold, maybe?)
-you don't have them for your MOE handguard