In using a guitar amp, it's important to know how to manipulate the amplifier to achieve a number of different effects, including a clean or dirty sound. Learn about using the bass and treble knobs on an amp with help from a professional guitarist in this free video on guitar amps.
A 10 X 13 envelope (must be less than 1/4 inch thick) is considered a flat and costs 80 cents for the first ounce and 17 cents for each fractional ounce after that up to 13 ounces.
However, Priority Mail includes labels and boxes that the Postal Service provides at no additional cost. All Priority Mail packages weighing 70 pounds or less cost the same flat rates. As of 2015, those rates are $5.95 for shipping a small box, $12.65 for a medium-sized box and $17.90 for a large box.