Retro Arms Gearboxes are manufactured from one block of aircraft aluminium (Dural) EN AW 7075 T651; they are milled on multi-axis CNC machines.
For comparison, the strength of aircraft aluminium (Dural) EN AW 7075 T651 is 550MPa, common construction steel has only 390MPa.
All of the gearboxes are designed for the best durability, resilience and strength on the most powerful springs.
These gearboxes are designed with full Tokyo Marui compatibility in mind.
Includes bearing bores for 8mm bushings or bearings (not included).
Please note these versions are Silver in colour.

2024 Version Gearbox Case:

Reinforced the integrity of the gearbox around the pistol grip.
Enlarged the holes for cables.
Enlarged front hole for cables for 416C compatibility.
Better cable routing around motor axis - added groove and nose as on V2 gearbox.
Improved bearing bore drilling - more accurate bore and larger tolerances on bearing diameters.
Enlarged grooves for the switch backdrop.
Enlarged cylinder bore.
Redesigned cylinder bore relief - created for maximum strength.
Redesigned cylinder mounting on 4 support points instead of full length - greater compatibility with multiple manufacturers.
Enlarged piston groove for increased gearbox life.
Edge removal - previously a cable routing issue.
Removal of radius - previously a problem with bolt movement.
Reinforcement around the cylinder in the rear.
Spring guide together with mech box in package to ensure full compatibility with retro arms piston.
Installation of the inner parts and gearbox requires professional knowledge, experience and skills. There are a lot of airsoft manufacturers on the market and every one of them create their own sizes, there are no standards like engineering ISO in airsoft.

Complete Gearboxes & Cases

Retro Arms CNC Gearbox NGRS 8mm