Marshall offers a wide range of speakers for different applications. Here is a list of some of the sizes of speakers that are available:

1. 5″
2. 8″
3. 10″
4. 12″
5. 15″
6. 18″

These sizes refer to the diameter of the speaker cone, and the size you choose will depend on the specific needs of your application. For example, a smaller speaker may be suitable for practice or home use, while a larger speaker may be more suitable for live performances or larger venues. It's also worth noting that Marshall offers a variety of speaker cabinets with multiple speakers of different sizes, allowing you to customize the sound of your setup.