Logitech Harmony Smart Hub O-R0004 with Remote Control 815-000100 and IR Blaster | eBay
Logitech Harmony IR Extender System
Logitech Harmony Hub Teardown - iFixit
Amazon.com: Harmony IR Adapters, Ancable 2-Pack 2.5mm Mono Plug to 3.5mm Mono Jack Connector for Logitech Harmony Hub and IR Blaster, IR Emitter Extenders, IR Repeaters, IR Receivers : Electronics