These Matrix springs are build after careful study of major Japanese spring sets providing all the features you'll look for in an AEG spring for maximum performance. It is made out of high quality anodized piano wire, with tension carefully measured. Systema's irregular pitch, Prometheus's Stainless steel material and PDI's durability are all features duplicated and found in a Matrix spring. Test shown that this spring will last you longer, is more durable and will out perform!

Features:

• Irregular Pitch Spring Coils: Variable Tension. Reduces stress, wear and tear for your Gearbox
• Made out of Stainless Steel. Increased tension and durability. Tension lasts 50% longer than other leading brands
• Designed for all version Airsoft AEG gearboxes
• 140% (M100) ~320~380 F.P.S.
• 150% (M110) ~330~390 F.P.S.
• 260% (M140) ~450~550 F.P.S.
• 300% (M150) ~480~600 F.P.S.