This is a Leapers, Inc. - UTG Rail known as the Model 4/15, model MTU015.
The UTG pro Model 4/15 Extended carbine length drop-in quad rail fits model 4/15 carbines with rails extending beyond front sight. It has picatinny rails with 19 top slots" 23 bottom slots and 25 left/right slots.
Features:
Black finish
Solid locking feature
18 UTG rubber rail guards included
Fits AR rifles