It's the ICS CXP-UK1. It's an M4 with a keymod system on for the handguard. Electric blowback.
I got the black and short variant like this. I just can't deal with all tan rifles so I pretty much always have black rifles. I also tend to stick to short carbines because I'm not a tall fella.
I'm looking forward to the blowback. I miss it. I used to have a G36K recoil shock which was blowback. But it was too long for me and I really hated the plastic that the manufacturer used. I ended up swapped it for a brand new ICS G33 which was a G36-alike.
Much nicer polymer for the externals. It also used M4 mags so I don't have to carry around lots of different mags. The one I got rid of was another M4 carbine which was really nice but I hadn't used it in ages and it wasn't good with single shot which is what the site I play at most now is.