The original CD single (sometimes mini CD single or 3-inch CD or CD3 in the US) is a music single released on a mini Compact Disc that measures 8 cm (3.1 in) in diameter, rather than the standard 12 cm (4.7 in).

Can you play a mini CD in a regular CD player?

As long as you have a CD player with a standard CD tray or deck, you are going to have no problems playing the mini-CD in your stereo system. However, CD slots found on compact CD players and car stereos are not capable of playing mini-CDs.

Are there different sizes of CDs?

Disc shapes and diameters

Standard CDs are available in two sizes. By far, the most common is 120 millimetres (4.7 in) in diameter, with a 74- or 80-minute audio capacity and a 650 or 700 MB (737,280,000-byte) data capacity.

Mini CDs, or pocket CDs, are CDs with a smaller diameter and one-third the storage capacity of a standard 120 mm disc.