REM-Fit provides a 15-year guarantee with all their mattresses, at no extra cost to the customer. To qualify for the guarantee, all mattresses must have been used on a supportive base or foundation, substantial enough to support the mattress and all occupants. REM-Fit may also refuse an exchange if the mattress is stained or marked in any way. They’ll exchange any mattresses with manufacturing faults, though if the replacement mattress is higher in cost than the original, you will be expected to pay the difference. The 15-year guarantee doesn’t start afresh with the replacement mattress but continues from the delivery date of the original.