There are two types of implied warranties: the implied warranty of merchantability and the implied warranty of fitness. Virtually every consumer product you buy comes with an implied warranty of merchantability. This is an assurance that a new item will work if you use it for a reasonably expected purpose. For used items, the warranty of merchantability is a promise that the product will work as expected, given its age and condition.
The implied warranty of fitness applies when you buy an item with a specific (even unusual) purpose in mind. If you relate your specific needs to the seller, and the seller assists you in selecting the item, the implied warranty of fitness assures you that the item will fill your need. For instance, if you tell a retailer that you need a sleeping bag for sub-zero weather and the retailer sells you such as bag, it comes with an implied warranty that the sleeping bag will keep you warm in sub-zero temperatures.
In most states, an implied warranty lasts for four years. In a few states, however, the implied warranty lasts only as long as any express warranty that comes with a product.
Sellers sometimes try to avoid implied warranties by selling a product "as is." In order to effectively negate implied warranties, however, the seller must follow state law requirements. For example, some states require that the disclaimer be in writing and the language be obvious. A few states don't permit "as is" sales. Also, implied warranties can't be disclaimed when there is an express written warranty that comes with the product.