The Leak Saver will seal small leaks in systems where the full refrigerant charge is not lost within 7 days. We have heard of clients sealing large 48 hour leaks with our product; however, it is about a 50% chance that it will work.We measure a leak's size by time instead of diameter. We do this because we do not believe it is practical (or possible) to physically measure a pinhole leak in the field. The easiest and most practical way to determine a leak size is by how long it takes for the refrigerant to leak out.