IOS FACTORY S-System for Shimano #Silver

The IOS S-system is a drag unit and custom parts that enable hooking with greater hooking power while maintaining the smooth drag characteristics of Shimano reels.

The concept of a high-precision spool rotation and a high-precision bearing, instead of a resin collar with unstable surface pressure, which is brought about by the one-piece aluminum machine-cut housing, is a key element in the development of the new drag system. The concept of the spool being supported by a high-precision bearing, rather than a resin collar with unstable surface pressure, ensures that the surface pressure of the drag felt is always maintained at a constant level, increasing the stability of drag operation and enhancing drag characteristics, and minimizing drag output linearly in accordance with tension.

It is also effective for hooking fish around structure and on long casts, and for power game with large hooks, which cannot be caught with just a smooth hook.
The tone of the drag has also been refined and fine-tuned to a more precision instrument-like high pitch and presence with texture, with a finely tuned pitch that does not detract from the drag performance.
In addition, an adjustment shim is included to prevent uneven taper winding of the spool, making it compatible with a variety of reels.