When
construction is your game, a plate is a
rectangular piece of
metal, usually
structural grade ASTM A924 coil steel, with a whole
crap load of metal
teeth, about a quarter
inch long, sticking out of one
side of it. They are used to hold
together the
joints in wooden
trusses. Newer plates are
coated with an
oil to
deter rusting.
Plates are sold by the box or by the bundle. A box of plates is sold by weight rather than count, though it's almost always the same. Bundles are held together with plastic bands, and hold twenty plates.
A plate's size is given in inches by inches. For example, the smallest plate I've seen is the 2x3. Let's say you need to know the size of a plate you've found, but you've got no measuring tape. The simplest way is to look at the holes in the plate. Wherever there is a tooth in the plate, there is a hole, rectangular in shape, about two-thirds of an inch long and an eighth of an inch wide. If a plate is a 2x4, there will be four holes length-wise, down the plate. In other words, there will be four rows of teeth in the plate. As for the width of the plate, about 5 holes width-wise equals an inch. After working with plates for a couple of months, you should be able to identify any commonly used plate by sight.
The most commonly used plates are stored in boxes. With boxes, you get more volume than with bundles, so you get more plates. Plates sold in bundles are not usually used on residential projects, and are usually very large.
Caution must be exercised when dealing with plates! These are metal plates of pain with hundreds of tiny pokey metal gougers on them, and they're coated with oil, which stings a lot when you get it in a cut! It is a good idea to wear strong leather gloves when dealing with plates in bulk. Never throw a plate in the direction of another person, and yell at anyone who does. Always pick up unused plates at the end of a project. You don't want your table man to take a knee on one of these bad-boys. Also, plates are not inexpensive. You may just see some metal lying around, but your supervisor sees dollar bills.
In conclusion, plates are your friend. If you use them properly, you can make some sweet cash. Oh yeah, buddy.