The slot pattern on a shelving upright is a quick guide to its duty class.
- Butterfly hole – light and medium-duty boltless shelving, shelves clip in without bolts, about 600 kg per level on medium-duty.
- Figure-8 hole – medium-duty, around 800 kg per level with reinforced shelves.
- Diamond hole – heavy-duty, 1000 kg per level on longspan shelving and 1.5 t per level on pallet racking beams.
Capacity also depends on steel thickness, shelf reinforcement ribs and beam section – always ask for the test report for the exact configuration.