The flute refers to the wave-shaped corrugated paper glued between the linerboards. Different flute heights provide distinct balances of cushioning, strength, and print smoothness:
| Flute Profile | Flute Thickness | Flutes per Meter | Primary Benefit | Best Application |
|---|---|---|---|---|
| A-Flute | ~5.0mm | ~105–115 | Maximum shock cushioning | Heavy fragile items, transit cushioning |
| C-Flute | ~4.0mm | ~120–135 | Best all-round stack strength | Standard courier shipping master cartons (RSC) |
| B-Flute | ~3.0mm | ~150–165 | High puncture resistance | Canned goods, postal mailers, counter displays |
| E-Flute | ~1.5mm | ~290–310 | Superb flat print surface | Retail mailer boxes, cosmetics, subscription boxes |
| F-Flute | ~0.8mm | ~410–430 | Micro-flute, paperboard alternative | Small consumer electronics, luxury retail cartons |
### Dual Flute Combinations (Double Wall):
- BC-Flute (~7.0mm): The heavy-duty standard for export and warehouse stacking.
- EB-Flute (~4.5mm): Combines E-flute print quality on the outside with B-flute internal impact protection.