Free spinning center enables smooth line movement for technical dives
Seamless integration with SubGravity RES for easy installation
Improves handling of sinker and ball and braid systems
Durable construction for long-lasting performance
Summarized by Shop
SubGravity - FSI (Free-Spinning Spool Insert)
The FSI (Free-Spinning Spool Insert) is designed as an upgrade for the SubGravity RES (Ridiculously Enhanced Spool). This insert fits seamlessly into your RES to provide a free-spinning center for the diver to more easily run line, shoot SMBs, etc.