The largest category of tube light in widely-available use, T8 tube lights measure 26mm in diameter and are often used for lighting large, wide-open spaces.
They're normally seen in supermarkets, warehouses, garages and offices, although they're suitable for smaller environments that need plenty of light too.
Like T5 lights, T8s are excellent at colour rendering, so you can count on them to deliver the clarity and colour temperature you desire - they're also available in colours like red, green and blue if you need to light a space in a specific way. T8 lights can also be used with specular reflectors to maximise their light output.
Take a look at the fluorescent tubes found below, and get the most out of your lighting.