Kronos + Mercury Spring + Jupiter (Strong-prime) 140FPS average (NEW 2019 version!)

NOTES FROM LUKE:
The Kronos Spring (Strong-Prime) is a 3.7" custom made spring that offers a 140FPS average after a simple installation. This mod is not for kids! You will need strong hands to prime this spring. Want something lighter? Check out my K25 Kronos spring here: 

https://outofdarts.com/products/new-kronos-3-7-k25-spring-hand-cut-easier-prime-120-125fps-average

FEATURES:
-Simple installation
-Both ends are flat/squared
-Around 135FPS can be expected

-Easier to prime than the previous version, yet higher FPS!