The 
T&D AR buffer tube sling mount
 appears to be a sling attachment point that is part of the "T&D" line of airsoft accessories, designed for M4/AR-15 Airsoft Electric Guns (AEGs). The device replaces the standard receiver end plate and is designed to provide a quick detach (QD) sling attachment point for ambidextrous use. 
 
 
Product Details
Attachment Method: This product is a sling plate (receiver end plate) that mounts where the buffer tube meets the lower receiver on an M4/AR-15 AEG.
Sling Compatibility: It provides QD (Quick Detach) sockets on either side, allowing for both left and right-handed configurations and quick removal of the sling.
Material: The sling plate is typically made of alloy, and it usually comes with a steel QD sling swivel for durability.
Installation: Installation involves removing the stock and the existing buffer tube end plate, then replacing it with the T&D mount before reassembling the stock.
Intended Use: This accessory is primarily marketed for use with airsoft replicas (AEGs/GBBs), rather than real firearms.