This is a Nordic Components Handguard known as the NC-1, model FFT-NC1-XL.
Nordic Components NC-1 Free Float 15.5" Extended-Length Handguard Assembly Is compatible with most AR15-pattern upper receivers and Nordic AR22 stock kit. Thread mounting points accommodate Nordic rail sections. Not M-LOK compatible.
Features:
NC-1 Free Float 15.5 Extended-Length Handguard Assembly;Not M-LOK compatible