- the size 10 is an indication in mm. there are small deviations per brand
- the tube size in this example is 2.6 is exact - choose it equal to or one step larger than the top diameter
- exception for guides with incert - size 40 the outer dia. of the incert is 34 to 36 mm depending on the brand
- for guides without an incert such as Seaguide ABTDG is outer dia. frame approx. equal to the size specification