Benchtop supplies come with various features and voltage/current ratings, though the most common is a +12 VDC unit. Some have adjustable voltage output, one will even act as a constant current source. Current capability is directly related to pricing on power supplies, and you should try to get a supply with enough current capability to meet your needs. For example, if a device pulls a maximum of 10 amps, the tendency will be to purchase a 10 amp supply. This leaves no “headroom” at all for the power supply and will cause it to work at the extreme of it’s capability all the time.