They will accommodate some of the entry-level Xiaomi Scooters and being small can often be fitted (probably inappropriately) into larger round callipers as they use the magnetic attachment. You would go the larger pad if appropriate, although these pads aren't used aggressively and usually have pretty long service intervals (several thousand kilometres).
Supplied as a set (pair) two pads, one for each side. Order two sets for both front and rear.
Available in three compounds. To further understand merits of each compound, refer to the Brake Pads Category homepage.