SA-F04 FLEX Gen.2 BLDC HAL ETU Half-Tan Airsoft rifle

The SA-F04 FLEX Gen.2 BLDC HAL ETU Half-Tan Airsoft rifle from Specna Arms is engineered for players who demand factory-level performance with room to tailor to their play style. Built around a high-torque BLDC motor, this carbine delivers immediate trigger response, reduced heat buildup, and longer service life thanks to a brushless transmission that minimizes wear and sparking even under rapid fire.

To maximize accuracy and consistency, the HAL ETU system integrates precise trigger sensing with programmable fire modes, automatic pre-cocking, and a low-battery alarm. This means you can push hard during skirmishes without worrying about reliability. The auto and semi modes are designed to cover a wide range of engagement scenarios—from controlled long-range shots to rapid close-quarters exchanges.

Explore the SA-F04 FLEX Gen.2’s core architecture:

• BLDC motor for sustained performance – no brushes means less wear, cooler operation, and higher efficiency at high speeds.
• HAL ETU control – magnetic trigger sensing, active brake, and a binary trigger option for decisive, programmable fire control (including auto, semi, 3-round burst, and 5-round burst).
• Top Down Center (TDC) Magnus Hop-Up chamber – unparalleled adjustment stability and precision in every shot (patented in Europe under 015052069-0001).
• Helium Flat Hop Eraser – improves backspin consistency and flight stability for tighter groupings at range.
• Æther Gearbox – reinforced frame with pre-cocking, AoE inspection windows, and spring compatibility up to M140 without sacrificing performance.
• Aluminium sealed nozzle – reliable seal and consistent air throughput under heavy use.
• Industrious build – nylon fibre-reinforced polymer body with critical metal components (flame suppressor, external barrel, bolt-catch, safety levers) for a balanced, durable platform.
• Ergonomic, ambidextrous design – enlarged selectors and magazine release for fast manipulation in any position.
• Light Ops Stock – compact, low-weight stock with non-slip cheek stickers and a curved rubber stock foot for shoulder stability.
• Factory readiness for upgrades – designed to accept a wide range of hard springs and aftermarket components without performance degradation.

Why the SA-F04 FLEX Gen.2 stands out

In the field, reliability and precision matter as much as raw firepower. The Gen.2 upgrades focus on repeatable accuracy, quick follow-up shots, and ease of maintenance. The combination of the BLDC motor, HAL ETU control, and the TDC Magnus Hop-Up creates a platform that remains stable across speeds and temperatures, making it a dependable choice for both tactical drills and intense skirmishes.

For users seeking to keep a low profile while maintaining high impact, the Half-Tan finish blends with urban environments and CQB setups, while the strong yet lightweight nylon-polymer chassis keeps the rifle maneuverable in tight spaces. The model’s notable materials mix—the majority nylon reinforced polymer with strategic metal parts—delivers a durable yet balanced feel in the hands, not a heavy, top-heavy build.

The AUTO function adds a practical edge: a controlled three-round burst precedes full-auto, giving you a predictable spread when you need it. The HAL ETU’s programmable semi/binary/AUG/sniper modes expand your options without requiring external tools, while the trigger-sensitivity adjustments (five levels) let you fine-tune response to your trigger pull.

Who this rifle is ideal for

• Players who want a high-performance, out-of-the-box platform that’s ready for precision upgrades and tune-ups.
• Players who value programmable fire control and ambidextrous ergonomics for fast-paced gameplay.
• Teams and individuals looking for a robust, field-tested platform with a proven gearbox and chamber design for long-term reliability.
• Fans of Specna Arms who seek the brand’s expertise applied to a versatile, competitively priced carbine.

Practical use cases and scenarios

• Urban CQB and close-quarters engagements benefit from the compact carbine profile, quick target transitions, and reliable trigger response.
• Mid-range field games are supported by stable hop-up via the TDC Magnus chamber, enabling consistent accuracy at practical distances.
• Layered loadouts can leverage the HAL ETU’s multiple modes for scenario-specific fire control—semi for stealth engagements, binary for decisive rushes, and triple/quad bursts for suppression.

Interested in more from the Specna Arms lineup? See more from the Specna Arms collection and explore related high-performance carbines in our Airsoft Rifles collection for options that align with your playstyle and budget.

Build quality, ergonomics, and maintenance tips

• The Hurried out-of-the-box experience is supported by reinforced frame design, which prevents frame flex under load and maintains consistent AoE alignment.
• Regular inspection of the TDC Magnus Hop-Up assembly ensures windage and elevation remain stable after extended use.
• Keep the nozzle and hop-up components clean to preserve the precision of the Helium Flat Hop Eraser and consistent BB backspin.
• Lubricate the gearbox and moving joints with light oil designed for airsoft to optimize response and reduce wear on the Æther shell components.

For additional options and compatible upgrades, the Specna Arms platform is designed with modularity in mind, allowing you to tailor torque, response, and trigger feel to your local field rules and style. The rifle is ideal for players who want a high-performance base that can evolve with their engagement strategies over time.

Ready to expand or customize your build? Explore the Specna Arms collection to compare variants and configurations that complement the SA-F04 FLEX Gen.2, then pair with compatible accessories and magazines to suit your preferred loadout.

Battery included	No
Bearings diameter [mm]	8
Blow Back	No
Colour	Half-Tan
Product length [cm]	75.50
Product weight [g]	2145
Power supply	Electric
Material	Aluminum Plastic
Muzzle velocity [FPS]	390
Fire mode	Full-auto Adjusted burst Semi-auto
Gearbox version	Gearbox v2
Hop-Up	Yes
Inner barrel length [mm].	230
Length minimal [mm]	670
Magazine capacity [pcs.]	125
MOSFET/ETU	Yes
Quick Spring Change system	Yes
Type of plug	DEANS / T-connect
Type of thread on the barrel	14mm CCW