I grabbed what I thought were the right rollers, only to realise the handedness was off when they arrived. Emailed support with photos, got a polite reply explaining the difference and pointing me to the correct set. I returned the first order and paid my own postage back, then reordered. Replacement shipped promptly and came in well packed. Slight hassle, but I appreciated the clear guidance and the fact they stock parts for doors older than my house.