Plates come in two main materials. Nylon and Aluminum.
Below is a list of pros and cons on aluminum vs nylon plates:
Nylon plates are lightweight and are often found on less expensive skates. Sometimes the nylon plates are referred to as plastic.
Nylon plates can flex if you go up on your toe stops, which is common for some styles of stopping or some styles of quick take offs. The nylon plates flex can absorb some of the momentum when taking off making it not as advantageous for sports like roller derby.
Aluminum plates are also preferred for being less likely to break if used frequently, roughly or by a larger skater.
Lower priced aluminum plates have a tendency to be bit heavier and this can make skating a little more difficult for a smaller skater.
Higher end aluminum plates are lightweight like a nylon, but with the durability of an aluminum plate. They are the ideal in skate plates.
Axles are commonly available in two sizes. 7mm or 8mm. Most older skates have a 7mm axle, but most skate plates manufactured recently are in 8mm. Why the difference? Speed skaters preferred the 7mm axles in the past in an effort to reduce weight of their skates, now most prefer the durability of an 8mm axle. Some plates are available in both sizes, and a matter of personal choice. This does affect what bearing size you will need. Make sure if you are going to be using bearings you already have that you take that into consideration, or purchase the correct size for the axle you are selecting.
Action – Single vs Double
Single action simply means that there is only one cushion on the plate on each kingpin, below is a picture of a single action skate truck:
Double action equals two cushions, one on each side of the truck on the kingpin of the skate plate. Most skates now offer double action because it gives you more play (maneuverability) when skating. Below is a picture of a double action truck for comparison.
King Pin Angle
Most skate plates commonly come with 45 degree angle or 10 degree angle. There are a few other angles, but most come in either 45 degree or 10 degree angle. Both styles can be advantageous for a variety of skaters. More elite skaters usually know which degree they prefer for their style and will stick with that at all times. Newer skaters may find it best to use the following suggestions, or experiment with both and see which one best suits their style of skating.
10 degree plates tend to give a more stable feeling, because the kingpin and cushions are located more vertically under the skater. This is definitely the most common style.
45 degree plates have become very popular particularly with roller derby skaters. The cushions are positioned almost horizontally, this makes the skate more responsive to direction changes. Make quick changes in direction easier and quicker. This is commonly referred to in roller derby as cutting, used to quickly get across the width of the derby track to stop an opponent. This is a 45 degree angle plate, you can see how the kingpins point to the side more than a typical plate.