Omnispool’s Arbor Spacers for the Omnispool system speeds loading and reduces line memory from tight winding. Spare fly lines are spooled, stored and packed, not to mention accessibly tangle free when you need them, in a jiffy. Easily snaps into your Omnispools (sold separately). Two arbors with diameters 2 1/8 in. and 2 3/4 in.are included in each pack. (Omnispool hub diameter is 1 1/8 in.)