FrSky Tandem X18S
 
The X18S is a highly sought after radio since it was only made for a short period, it was discontinued to make room for the X18SE. There are only a couple of these left brand new in the world. 
 
When you are investing in a new radio and considering what requirements are important to you, if weight and comfort are primary considerations, followed by the benefit of the excellent system features of ETHOS, then the FrSky Tandem X18 series radios are obvious appropriate choices.
 
The Tandem X18 series dual-band telemetry radios benefit from an enhanced ergonomic design with rounded and more comfortable hand grips, along with an improved case design to make the radio fully stable when standing. The radio includes easy-to-reach sliders and switches, 4 standard stick trims with additional 2 extra trims added to provide more flexibility with flight attitude adjustments while operating the radio. The X18 series include further enhancements with integrated flash storage which improves and simplifies storage operation and use, and the interior of the radio has been designed with space and weight in mind, while still keeping all ETHOS setting and control features for the pilot to enjoy.
 
Internal 900MHz/2.4GHz Dual-Band & External Module Bay
The TD dual-band RF system combines both the features and advantages of FrSky 900MHz and 2.4GHz RF together in one system. The TD features real simultaneous dual-band longrange control with telemetry that achieves reliable end-to-end 4ms latency while maintaining a robust and high-quality signal link. The entire range of TD, ACCESS & ACCST D16 receivers are supported. The built-in TANDEM RF System supports ACCESS and ACCST D16 protocols.

In addition, the Tandem X18 series radios include a rear Lite version module bay to offer more options to connect external devices. FrSky welcomes working compatibility with the 3rd party products with their own developed technology following FrSky verified 3rd party compatibility-testing program.
 
 
Why We Recommend This
The X18S is the premium X18 — Hall sensor gimbals, dual-band Tandem TD coverage, and ETHOS in the familiar X18 form factor. Our pick for intermediate to advanced pilots who want the full X18 platform spec without moving to the larger X20 class. FPV Builds RC provides U.S.-based product support, transmitter-setup assistance, and configuration guidance for FrSky radios purchased through our store.
Frequently Asked Questions:
Which receivers are compatible with the Tandem X18S?
The X18S is compatible with all three FrSky receiver families: Tandem (TD) dual-band receivers (TDR10, TDR12, TD SR10, TD SR12, TD SR18) for the best range on both 2.4GHz and 900MHz simultaneously; ACCESS receivers (Archer Plus series); and ACCST D16 receivers for legacy compatibility (older units may need a firmware update). Browse our full receiver selection: https://www.fpvbuildsrc.com/frsky-receivers
What is the difference between the X18S, X18SE, X18RS, and X18?
The X18S is the core dual-band Tandem flagship of the X18 line. The X18SE is a special edition variant with refined ergonomics and a unique colorway. The X18RS adds the TD-ISRM RS module for a dedicated 900MHz long-range mode. The base X18 is the original entry to the X18 family. All share full TD receiver compatibility and run ETHOS OS. Compare the lineup: https://www.fpvbuildsrc.com/frsky-transmitters
What firmware/OS does the X18S run?
ETHOS OS — FrSky's color touchscreen OS with OTA receiver firmware updates, telemetry widgets, and full mixer support. Free updates available from FrSky's firmware site.
Does the X18S have an external module bay?
Yes — a full-size JR-compatible bay. Run ELRS, R9M, or any JR-format RF module alongside the built-in Tandem system for flying any protocol your aircraft requires.
What accessories are compatible with the X18S?
CNC Metal Tray: https://www.fpvbuildsrc.com/product-page/frsky-cnc-metal-tray-for-tandem-x20-x20s-x18-series and Shoulder Strap: https://www.fpvbuildsrc.com/product-page/frsky-transmitter-shoulder-strap
Does the X18S support FrID Remote ID?
Yes — the FrSky FrID module satisfies FAA broadcast Remote ID requirements and is compatible with the X18S: https://www.fpvbuildsrc.com/product-page/frsky-frid-remoteid-module-tailored-for-faa-compliance
Does FPV Builds RC offer support for the X18S?
Yes — we're a U.S.-based FrSky dealer. Contact us for receiver pairing, binding, and ETHOS setup assistance.