"Link to product: http://www.brillarmory.com/index.php?...

1. Reduction of wall thickness - it can be used in all M4 guns without problems.

2. Reduction of plugs for cylinder head -- Cylinder heads from all makers can be used.

3. Window for AoE

4. Window for checking the piston position.

5. Removal of radiuses around trigger contact areas - ASCU contacts can now be used without problems.

6. Gearbox can be..."