LD Systems easy-to-use in-ear monitoring systems with earphones are also available as in-ear wireless systems, with the transmitter and receiver also available separately.
GAW-M9200 Professional stage wireless monitor in ear monitor system performance monitor earphones
Ultimate Ears Professional Custom In Ear Monitors – Ultimate Ears PRO
Taylor fixing her in-ear monitor on stage (Los Angeles Night 4) : r/TaylorSwift
An abundance of power with a punchy low end and plenty of articulation that comes from a boost in the mid-high end make the Tour the go-to monitor for
Tour Triple Driver
How Taylor Swift Stayed on Track When In-Ears Failed During Eras Performance
Floor Wedges Vs. In Ear Monitors: Comparison and Pros & Cons – Arkartech
Getting Started with In-Ear Monitoring
Mono Outputs, PLL Synthesized circuit. LCD display shows the RF level, AF level, channel and frequency. 1X Audio cable. Transmitter Power: 30mW. 1X
Personal Monitoring Systems for the Studio and Stage IEM In-Ear Wireless System
ASI Audio by Sensaphonics
Custom and Universal In-Ear Monitor Store - Alclair Audio
IN EAR MONITOR MIX (wear earphones) DON'T BLAME ME [THE ERAS TOUR STUDIO VERSION]
The Evolution of In-Ear Monitors – PS Audio
Some more @Taylor Swift in-ear monitor (IEM) audio from the 1989 World