C5 is a Continental grade permitting quills up to 12 mm across, with a minimum of 27 whole quills per kilogram and up to 15% foxing.
The thicker wall holds its shape well during long simmering, which suits curries, stocks, mulled drinks and any preparation where a quill is infused and then removed.
C5 Special is narrower at 10 mm with a tighter 10% foxing limit; C4 is wider again at 16 mm with 22 quills per kilogram.