All 12B Krieghoff factory and titanium choke tubes are numbered as follows:
| No: | Size | Diameter | US | Eng |
| 00 | 0.00" | .732" | Cyl | Cyl |
| 0 | 0.05" | .727" | Skeet | Imp Cyl |
| 1 | 0.10" | .722" | Imp Cyl | 1/4 |
| 1+ | 0.15" | .717" | Light Mod | 3/8 |
| 2 | 0.20" | .712" | Mod | 1/2 |
| 2+ | 0.25" | .707" | LIM | 5/8 |
| 3 | 0.30" | .702" | Imp Mod | 3/4 |
| 4 | 0.35" | .697" | Full | Light Full |
| 5 | 0.40" | .692" | S.Full | Full |
