known as an 8-page or a right angle. More folds can be accomplished by the use of a 16-page and 32-page unit. Entry-level paper folders require that the folding plates be adjusted manually, with fold settings specified on the folding plates. Higher-end paper folders will electronically adjust the folding plates for added precision and convenience. Both usually have fine tuning knobs for precise adjustments. Most paper folders push paper into the machine by use of a friction wheel; this grabs paper using friction. Friction-feed paper folders do not work well with glossy paper as the friction wheel slips on the paper's surface. Pneumatic paper folders are preferable for folding glossy paper. Due to rarity they've made their way in to collector archives for obsolete office equipment. Along side fax machines and paper drills, they are known for being inefficient in the modern workplace. Pneumatic folding machines Pneumatic paper folders push paper into the machine using a vacuum. These folders are often referred to as air-powered paper folders. This method makes it possible to fold most types of paper. Most pneumatic paper folders include a built-in compressor. These folders can have as many as sixteen folding plates or several knife folds depending on the imposition, these are adjusted manually or electronically, depending on the machine. Feeding systems There are 2 types of feeding systems used by folders, pile and continuous. The first is flat pile, in which the paper is placed on a feeding table and each sheet is then transported into the machine by friction or an air-controlled suction-wheel. A variation of this is palletized feeding, in which an entire pallet full of paper may be placed on the feeding table. The second type is called "continuous"; this involves the sheets being placed onto a belt, on a table or rollers, that takes it around the end of the machine, then each sheet is individually pushed into the machine by an air-controlled suction-wheel. The sheets of paper will be separated by blowing air between them. Folder inserters Folder inserters are designed for mailing bills, checks and other material. Folder inserters take paper, fold it, insert it into an envelope and seal the envelope. Folder inserters are available in several designs, many equipped with multiple feed trays for several sheets of paper. Many have the ability to include inserts and return envelopes. These are mixtures of knife and buckle folders. Folder