Fits to Shimano 19Antares reels. 4.1mm shallow spool weighs at 7.5g, instead of 10.9g of stock spool.
The ultra light spool accelerate fast with light rigs of 3.5g well. You will swap the SVS brake holder from stock spool using Avail SVS puller Infinity. Or, use with magnet brake MB-19ANT listed below of the product page.