Bing found the following results
The Mat-9 Close Combat Carbine - Matador Arms LLC
MAT-9 9mm AR Upper - Matador Arms LLC
MATADOR ARMS MAT-9 9MM UPPER RECEIVER
MATADOR ARMS MAT9 Upper Receiver 9mm Review - TheGunZone
Matador Arms MAT-9 9MM Blowback Upper Receiver
Matador Arms Introduces MAT-9 Upper Receiver - Soldier Systems
Matador Arms 9mm MAT-9 Upper Receiver: A Self-Contained …
Exploring the MAT-9: Innovative 9mm Upper & Fully Ambi Lower …
Matador Arms | MAT-9: The Universal 9mm Upper | SHOTShow …
MATADOR ARMS MAT9 UPPER RECEIVER 9MM - Brownells