A useful organiser starts with the space you have, not the size it appears in a photo.
Measure the space
Measure usable internal width, depth and height. Allow for drawer runners, hinges and space to open a lid. For under-bed storage, check clearance and whether the filled bag can slide out.
Check the exact fit
Match the selected size and pack quantity to your measurements. Check the adjustment range of dividers and whether quoted dimensions describe the outside or usable storage space.
Know the trade-offs
Soft bags may slump rather than stack. Look for comments about weak seams, zips and handles. Pressure-fit dividers or adhesives may mark surfaces; do not assume fabric storage is moisture-proof.
One final check: compare recent customer photos and critical reviews for the exact variant. Confirm the total delivered cost before buying. These are buying checks, not claims of hands-on testing.