Prometheus Non-Linear Upgrade Spring for Airsoft AEGs (Model: MS135 / Crimson)

Upgrade your AEG with the Prometheus Non-Linear Upgrade Spring MS135 (Crimson), a high-performance internal part designed for serious Airsoft players looking to boost their rifle’s power and consistency. Built with precision and quality in mind, this upgrade spring is part of Prometheus’ premium series, manufactured by Laylax — a trusted name in Japanese Airsoft engineering for over two decades.

The Prometheus MS135 is designed to deliver approximately 450 FPS when paired with 0.20g BBs, making it ideal for players participating in outdoor field games where extended range and power are essential. Thanks to its non-linear spring design, this upgrade provides a smoother compression cycle compared to traditional linear springs, which helps reduce stress on your gearbox while delivering consistent muzzle velocity with every shot.

Crafted from high-quality spring steel, the MS135 offers excellent durability and longevity under intense use. The steel construction also ensures minimal power loss and consistent energy transfer, which translates into better shot-to-shot reliability and increased accuracy downrange. Whether you’re pushing BBs through a long inner barrel or engaging from a distance with a DMR-style build, this spring is built to meet your performance needs.

One of the standout features of the MS135 is its intelligent design. The “135” designation follows a metric-based naming convention, reflecting meters per second (m/s) performance—making it easy to identify its approximate output at a glance. The spring is also color-coded in Crimson, allowing you to quickly sort and identify it in your parts bin even if the original packaging is lost.

This spring is compatible with most standard TM-spec AEG gearboxes, including popular models from Tokyo Marui, EMG, Matrix, and other brands that follow the same internal design. That makes it a versatile option for builders and techs who want a reliable performance upgrade without having to worry about cross-brand compatibility issues.

Thanks to its non-linear coil structure, the MS135 reduces initial compression resistance, making it easier to install and improving energy efficiency throughout the firing cycle. This design also helps minimize wear on other internal components such as the piston and gears, especially during rapid or prolonged firing sessions. The result is a balanced performance upgrade that doesn’t compromise the long-term health of your rifle’s internals.

Installing the MS135 spring allows you to custom-tune your AEG to match specific field limits, scenarios, or personal preferences. Whether you’re building a powerful outdoor rifle for long-range engagements or tuning a DMR platform to hit harder and more consistently, the MS135 offers the reliability and performance edge you’re looking for.

Specifications:

• Model: MS135 (Crimson)

• Velocity Output: Approx. 450 FPS with 0.20g BBs

• Compatibility: For most TM-spec AEGs (Tokyo Marui, EMG, Matrix, and similar)

• Material: High-quality spring steel

• Color Code: Crimson for easy identification

Note: The actual FPS result may vary depending on installation quality, gearbox alignment, barrel length, air seal, and other internal components. Always test FPS with a chronograph after installation to ensure compliance with field regulations.

About Prometheus & Laylax:
Prometheus is a product line under Laylax, a Japanese manufacturer known for its unmatched quality and engineering precision. Laylax has been a leader in the Airsoft industry for over 20 years, creating upgrade parts and accessories that continue to set the standard for performance and durability.

Whether you’re a field-ready pro or a technical enthusiast working on a custom build, the Prometheus MS135 non-linear upgrade spring offers a perfect combination of strength, precision, and reliability—making it an essential upgrade for any high-powered AEG platform.