By improving line rollers rotation, this custom line roller improves retrieve sensitivity, reduces line trouble, and is also wrapped in line on the spool, ensuring a stable release during casts, allowing you to experience better distance of the guide knook. Even when the lure is not attached, you can see the rotation of the line with its dot-hole movement with excellent designability. In fact, it does not spin like a line roller. Even when handling line slacks or retrieving lures with low resistance if not always spin, the braided line will be wrapped in the spool when casting. It also leads to the cause of rash. The no-spin line roller not only significantly reduces retrieve sensitivity, but also leads to trigger various troubles, such as reduced distance and line issues. IOS line roller impact uses a line roller that is not possible to get through spinning. The line roller impact is a brand new concept that improves the distance of Shimano reel and increases wind sensitivity. *Line roller impact is a custom part that improves the rotation of Shimano reel line roller. Can also be used as a line roller. Replaceable but the core protection is a line roller with excellent waterproof, dustproof, and corrosion resistance, and the durability may be inferior compared to the original line roller with core protects. When installing a line roller, there may be some movement up and down the main unit. Please be aware that there is a gap that is necessary to reduce line strain and improve performance. However, there is no abnormalities, so please feel free to consult the manufacturer. Also, if you turn the reel quickly on it, the rotor may be shaken. We think this is a level of concern during normal lure retrieves, but please understand that this is a priority for rotating performance. Please be sure to attach the item that fits the reel when purchasing. If the size does not fit you well, it may not perform or be able to install in the worst case.