Car exhaust is an unhealthy result of fossil fuel use. Photo Credit exhaust fulmes image by bilderbox from Fotolia.com. Fossil fuels are among the most commonly used forms of energy in the world. Common fossil fuels include natural gas, coal and petroleum, which is refined to create gasoline.Although fossil fuels are strong sources of energy, their use can pose certain health problems if handled incorrectly.ar exhaust is an unhealthy result of fossil fuel use. Photo Credit exhaust fulmes image by bilderbox from Fotolia.com. Fossil fuels are among the most commonly used forms of energy in the world. Common fossil fuels include natural gas, coal and petroleum, which is refined to create gasoline.
First-Class Mail International is a USPS trademark. Note: The cost of postage will appear on all international shipping labels. Maximum weight for letters is 3.5 ounces. Maximum weight for large envelopes is 4 pounds.
Quick Answer. The maximum weight for a First-Class letter envelope, which is 3.5 ounces, according to the United States Post Office. There are also size and proportion requirements to consider when sending mail First-Class. Letter envelopes must be rectangular, and they must not exceed 11.5 inches in length or 6.125 inches in height.