Features:

• Oil Tempered with high pressure treatment
• Progressive design, or "Irregular pitch", minimizes spring resistance making it easier to pull the bolt back
• Constructed out of 1st class carbon steel piano wire
• Long lasting durability and high performance output

Spring Type: SP150 Irregular (Progressive)
Spring Velocity: 420~450 FPS (velocity will vary depending on modifications done to rifle, manufacturer of rifle, and internal parts used)
Compatibility: For UTG, Shadow Op, MB-01 and other compatible APS / Type96 series Airsoft Spring Sniper Rifles
Material: Carbon Steel piano wire