Backpack of Incredible Volume

People who buy this backpack will be amazed to see their items disappear when they put it in, relieved when they can take them back out. It doesn't take long to realize that ANY object put in there disappears but can be withdrawn. The Backpack leads to a pocket dimension approximately 10 to 20 times the normal volume of the backpack. In addition, the Backpack can still hold it's regular weight when the dimension is full; combining this enchantment with a Backpack of Featherlight, while highly expensive, can make a very effective travelling item. Only people very skilled at detecting dimensional/temporal anomalies can detect the difference.