Acid

A notebook (also known as a notepad, writing pad, drawing pad, or legal pad) is a book or stack of paper pages that are often ruled and used for purposes such as recording notes or memoranda, other writing, drawing or scrapbooking.

Consistent ink flow
Smooth and dark marking
Marks on CD, DVD, metal, OHP sheets, wood, plastic, glass and ceramics
Water resistant and UV resistant

An envelope is a common packaging item, usually made of thin, flat material. It is designed to contain a flat object, such as a letter or card. Traditional envelopes are made from sheets of paper cut to one of three shapes: a rhombus, a short-arm cross or a kite.