The #30 is designed to be used in conjunction with
Gem Circle Hangers (sold separately).
It is made to attach half-round gutters to angled fascia boards or exposed rafter tails. The holes allow for the extension portion of this shank to be adjusted to the desired angle / pitch.
The shank should be screwed to the roof. The Gem Circle Cradle Hanger can then be bolted to the shank.