Self-Inking stamps have a rubber plate mounted inside a stamp that sits on a small conventional stamp pad; when pushed down, the pad flips up and down to make an impression. They are good for around 4,000-6,000 impressions before re-inking, or a new pad is required. Pre-Inked stamps have an ink reservoir behind the imprint area and make a cleaner, sharper imprint and can use smaller text and come in much larger sizes than self-inking stamps. They are good for about 6,000-10,000 impressions before re-inking is required.