Economic profits in perfect competition and monopolistic competition market has a special purpose, a positive profit can attract more enterprises to enter the market, increasing competition and push the market equilibrium price low, exclude some enterprises lack of competitiveness in the market, to achieve long-term equilibrium; On the contrary, negative economic profit can eliminate some of the original enterprises in the market, because the supply is reduced, the market equilibrium price will be pushed up, and the long-term equilibrium will be achieved. The result of the two cases is that economic profits disappear from each manufacturer and the manufacturer's total income is at the lowest point of average cost. Valuation bubble Bed Prism Glasses or Lazy Glasses, because they are often called, are an aid to relaxation. They are used mainly take it easy during sex reading a book or viewing television or sometimes by patients during recuperation from illness or injury, where long-term bed rest is needed. Certainly not for anything that could be termed as a Sports Activity, besides watching the football on TV, during sex, perhaps!