For mics, ø19.0 mm (ø 3/4") to ø32.0 mm (ø 1-1/4") - all vanes fitted
For mics, ø32.0 mm (ø 1-1/4") to ø38.0 mm (ø 1-1/4") - remove every other vane

Designed for a Nano Shield NS4-DB