HSP Inc. does not accept any returns or exchanges on any product that has been installed and/or is in used condition. If you suspect your product is defective (as in, the tritium does not glow), the product will have to be returned to Heinie for inspection. Heinie cannot send out replacement products without having the originally purchased product in hand. If the item is determined defective, Heinie will send the sight out for the tritium vial to be replaced (in the originally purchased product). We do not replace the entire sight, only the tritium will be replaced. Turn around time to replace a broken or defective tritium vial usually takes about 3-4 weeks.