- Standard white core put no pressure on the silicone, creating smooth progression tension.
- Oversized black core will squeeze the silicone and add initial tension, reduce bounce back when return to neutral.
The spring also control the shaft spins, it pulled the shaft on the core, keeping the shaft from spinning and makes the handle easier to control.
Medium Spring and spare O-ring included on every GL Core. You can buy Light and Hard spring separately.
For more info about GL core you can this article.