An exit route must meet minimum height and width requirements. [29 CFR 1910.36(g)] The ceiling of an exit route must be at least seven feet six inches (2.3 m) high. Any projection from the ceiling must not reach a point less than six feet eight inches (2.0 m) from the floor.
4. adjective. In Britain, first-class postage is the quicker and more expensive type of postage. In the United States, first-class postage is the type of postage that is used for sending letters and postcards. Two first class stamps, please. The price of mailing a first-class letter will not be increasing this year.
With the United States Postal Service (USPS), one first class stamp buys you 1 ounce of postage, assuming you are using a regular-size, rectangular envelope. cf: Current Postage Rates, US Postage Stamp Prices.