Typically speaking, using regular notebook paper and a single envelope, 4 to 5 sheets of paper can be mailed while staying under 1 ounce. The United States Postal Service charges one stamp per ounce...
Exculpatory Evidence: Typically used in criminal cases, this type of evidence is that which favors the defendant, either partially or totally removing their guilt in the case. In the United States, if the prosecutor or police have found evidence, it is their duty to disclose it to the defendant.
The second type of evidence that can be utilized in an argument is opinion. In this instance, we are not talking about your personal opinion (the audience already knows your position in the matter!). Nor are we talking about the way you friend might feel about the issue.