This is an original hard EVA economizer for the Ambassador 4000 series fine-shaft spool. For fine-shaft spools with a spool shaft diameter of 10.4. Warning! Currently, installation has only been confirmed with the spool in the image. We will be checking other types of fine-shaft spools in the future. By attaching it to the genuine spool, you can create a shallow spool, eliminating the need for backing and reducing weight. The groove is approximately 6mm to the spool edge. Line Capacity (reference value) Nylon line: 16lb x 75-80m PE line: 3.5 No. x 75-80m (varies depending on the manufacturer) *For safety, double-sided tape for attachment is included, but it should not slip once the line is wound. (Be careful as it will be difficult to remove if attached with double-sided tape) *There may be slight variations due to being handmade. *The reel and spool in the photos are not included.