SA M4 Carbine M-LOK Gen2 (SA-F09 FLEX™ BLDC™ HAL ETU™) - Black / Tan

Specna Arms M4 Flex Gen2 – a fully upgraded rifle out of the box

Looking for a fully tuned M4 airsoft rifle with a light yet durable body? Want top-tier internals, a brushless motor, and an electronic trigger unit (ETU) inside? Need a rifle set with a suitable high-performance battery and the right charger so you don’t have to hunt for extras? Then this M4 FLEX Gen2 is exactly what you want. It’s the improved FLEX™ Gen2 series from Specna Arms that focuses on a low-weight nylon receiver while still delivering excellent fit and finish. The glass-fiber reinforced body is more durable than cheap zinc-alloy metal receivers—great for beginners and advanced players who favor fast, speedsoft-style gameplay where every gram counts. You’ll find this type of receiver, for example, on the CZ Scorpion Evo or MP7. The FLEX line is essentially the sibling of CORE, which uses CNC metal handguards, while FLEX uses a nylon handguard. The biggest Gen2 leap is inside: the internals are absolutely on par with the flagship PRIME™ series.
The M4 Carbine M-LOK Gen2 (SA-F09 FLEX™ BLDC™ HAL ETU™) comes with a fully reworked, reinforced gearbox dubbed ÆTHER that handles AEG springs up to M140. Inside you’ll find CNC steel 16:1 gears—an ideal ratio that, together with 8 mm bearings, delivers great rate of fire and durability.A reinforced 14-tooth polycarbonate piston provides ideal AoE and prevents lock-ups. It’s sturdy without slowing the shot. Air is directed to the chamber by a CNC nozzle mounted on a reinforced tappet plate arm.
The M4 Flex Gen2 also features the HAL ETU™ electronic trigger unit using magnetic sensors (Hall effect). Functions include active brake, binary trigger, adjustable trigger sensitivity, pre-cocking, programmable fire modes and a low-voltage battery alarm. For accuracy there’s a 6.03 mm inner barrel paired with a Helium Flat-Hop bucking in the redesigned MAGNUS™ TDC hop-up chamber. Spring changes take under a minute thanks to ESA2 quick-change. The whole BLDC™ setup is driven by a precision brushless Dark Matter motor with 27,000 rpm. It provides higher efficiency and performance, and boosts rate of fire and trigger response. It offers up to 5× more shots per battery (5000+ shots on 11.1V 1000 mAh). The motor sits in an aluminum housing for maximum durability and is suitable up to M190 springs.
On top of that you also get the Specna Arms EASY LIPO CHARGER set with an 11.1V Li-Po that fits the stock tube perfectly and a quality Li-Po charger.

HAL ETU™ unit and its functions

• trigger sensing based on magnetic sensors (Hall effect)
• active brake
• binary trigger (shot on press & on release)
• adjustable trigger sensitivity (5 levels, 20–100%)
• adjustable pre-cocking (6 levels)
• programmable SEMI modes (semi, binary, AUG, sniper with delay)
• programmable AUTO modes (auto, semi, 3-round burst, 5-round burst)
• easy programming via the trigger
• low-voltage battery alarm
• ideal for use with brushless motors (included)

Important first-use activation

To make the rifle fire, you must activate the HAL ETU and follow this procedure exactly—otherwise the rifle won’t respond to the battery:

1. Set the selector to Safe.
2. Connect the battery and wait 3 seconds until you hear a beep.
3. Press and hold the trigger for 5 seconds until you hear another beep.
4. The rifle is now ready to use.

FLEX™ receiver quality

The Specna Arms M4 Carbine M-LOK Gen2 (SA-F09 FLEX™ BLDC™ HAL ETU™) stands out with a high-quality nylon receiver featuring a matte finish and a very realistic look. Thanks to glass-fiber reinforcement it’s very durable and lightweight. The outer barrel is metal, and the screws, ejection cover and pins are steel. The ergonomic AR15 design and modern construction provide a comfortable grip and easy handling—this rifle just fits your hand! The M-LOK handguard lets you mount accessories like a grip, AN/PEQ box, flashlight, etc. With the adjustable Crane type stock there’s room for larger batteries (Buffer Stick, Nunchuck or Crane). Overall, it’s a rifle that combines low weight and premium internals with an attractive price.

FLEX polymer parts

• receiver
• stock tube
• handguard
• pistol grip, stock and sights

Metal parts

• outer barrel with 14-mm CCW thread
• flash hider
• charging handle for hop-up access
• steel screws, pins and small body parts

Technical Specifications

• Power: AEG
• Materials: Nylon, polymer, metal
• Length: 850-885 mm
• Weight: 2350 g
• Velocity: 115 m/s (1.4 J)
• Inner barrel length: 375 mm
• Inner barrel diameter: 6.03 mm
• Hop-up: Yes (TDC)
• Fire modes: Semi, Full Auto, Binary, Pre-Cocking and more
• Muzzle thread: 14-mm CCW
• Handguard: M-LOK
• Recommended battery: 11.1V Li-Po (included with charger)
• Connector: T-Dean
• Best battery type: Crane / Nunchuk / Buffer stick
• Magazine capacity: 125 BBs (Mid-Cap)
• Motor type: Brushless

Package Contents

• Specna Arms M4 Flex Gen2 AEG
• 2× S-MAG 125 BB Mid-Cap magazines
• Specna Arms 11.1V 1000 mAh (20C) Li-Po battery
• Specna Arms EASY LiPo Charger
• Speedloader for mid-caps
• Flip-up sights
• Spare M90 spring
• HAL ETU™ programming card
• Specna Arms stickers
• User manual

Warnings

• Some manufacturers’ springs are heavily overrated (e.g., an M130 can perform like M140–150) and may exceed the gearbox’s rated strength. Use only the included Specna Arms springs. For other brands, choose around M120 to avoid damage from mislabeled springs.
• If installing a spring with progressive/irregular coils, ensure the tighter coils face the spring guide outward from the gearbox.
• Never store the rifle with the battery connected.
• Never store the rifle with pre-cocking engaged. Always release the piston forward before storage to prevent spring damage.