OMM have a very modular design for all their packs, the downside of this is that it can be quite difficult to work out exactly what is compatible with what. The good news is most add ons fit with most packs. The better news is the table below gives a definitive answer as to what goes with what.
| Pack / Add On | Go Pod | OMM Leanweight | Compressor Pod | Chest Pod / Trio Map Pouch | H2OMM Bottle holder |
|---|---|---|---|---|---|
| Phantom 25 | Yes | Yes | Yes | Yes | Yes |
| Phantom 20 | No | Yes | Yes | No | Yes |
| Phantom 12 | No | Yes | Yes | No | Yes |
| Classic 32 | Yes | Yes | Yes | Yes | Yes |
| Classic 25 | Yes | Yes | Yes | Yes | Yes |
| Ultra 20 | Yes | Yes | Yes | Yes | Yes |
| Ultra 15 | Yes | Yes | Yes | Yes | Yes |
| Ultra 12 | Yes | Yes | Yes | Yes | Yes |
| Ultra 8 | Yes | Yes | Yes | No | Yes |
| Trail Fire Vest | No | Yes | Yes | No | No |
| Waist Pouch | No | No | No | No | Yes |
| Ultra Waist Pouch | No | No | No | No | No |
| Phantom Waist Pouch | No | No | No | No | No |