The theory is that to keep superlines from slipping, two circular grooves with a rubber O ring in each were added to the spool
Abu Dual Bearing Worm Kit, Black, with Ceramic line guide pawl: Achieve the ultimate in line lay and retrieve smoothness
3 Stainless steel ball bearings + 1 roller bearing(6500 size)
Expect: Maximum Casting Distance: Reduced friction from ceramic hybrid spool bearings, the dual bearing spool gear, ported idler, and bearing-supported worm kit all contribute to longer, more effortless casts
All the set-up is up front, you cast this reel without spool tension, depend on mag brake add-on to solve mid-cast wind backlash at the light end, and the stock centrifugal to solve start-up backlash with heavy weights