found this on an oregon store site....for what it might be worth
Based on the McCune-O’Donnell formula, Rod/Line match ups work out as follows:
7-weight rod matched with a 450 grain (7/8) Skagit line.
Rod length 13’6’’ or under go with straight Skagit 450 (no cheaters).
Rod length 14’ formula = 450 Skagit plus 5 (5 foot cheater).
Rod length 15’ formula = 450 Skagit plus 10 (10 foot cheater).
8-weight rod matched with 550 grain (8/9) Skagit line.
Rod length 13’6’’ or under go with straight Skagit 550 (no cheaters).
Rod length 14’ formula = 550 Skagit plus 5 (5 foot cheater).
Rod length 15’ formula = 550 Skagit plus 10 (10 foot cheater).
9-weight rod matched with 650 grain (9/10) Skagit line.
Rod length 13’6’’ or under go with straight Skagit 650 (no cheaters).
Rod length 14’ formula = 650 Skagit plus 5 (5 foot cheater).
Rod length 15’ formula = 650 Skagit plus 10 (10 foot cheater).
As you can see from the above the basic Skagit line/rod formula will depend on rod length with the enhanced use of the Skagit Cheaters (cheaters of matching size). The cheaters come in 2.5', 5’ and 7.5' lengths, to further customize your line to your specific rod. When selecting the appropriate set of cheaters follow the Skagit number, for example a 550 Skagit is a 8/9, use a 8/9/10 Skagit Cheater.
Below you will find a run down of Sage Rods with appropriate Skagit Line match-ups;
6126-4 Z-AXIS - Skagit 400, no cheater
7136-4 Z-AXIS - Skagit 500, no cheater
8129-4 Z-AXIS - Skagit 550 or 600, no cheater
8134-4 Z-AXIS - Skagit 550, no cheater
9143-4 Z-AXIS - Skagit 600 + 5’cheater or Skagit 650 + 2.5’cheater
10150 Z-AXIS - Skagit 700 + 5’cheater or Skagit 750 + 2.5’cheater
10150 Z-AXIS - Skagit 700 + 7.5’cheater or Skagit 750 + 5' cheater
Skagit Lines are purely a design for use with sink-tips. To be sure most fishing will be with type 6,8 and T-14 tips in 9,11,13,15 foot lengths. With 15’ being the standard sink tip length. Aqualux as well as type 3 tips can and will apply depending on strategy or seasonality.
However, Skagit Lines combined with either a floating or Aqualux tip have gained extreme popularity for fishing dry or damp when there is hard wind or lack of room to form a longer D-Loop. These short head lines are extremely easy for beginners to learn with.