Habitat drum length: 200m - 160km
Habitat drum diameter: 50m - 5km

Color Coding:
Red = Power Generation and Industrial Modules
Blue = Liquid and Gaseous Ressource Tanks
Orange = Logistics and Docking facilities
Yellow = Artificial Lighting
Green = Habitat Section

Construction materials:
Primarily steel and aluminium.
Larger diameter stations use maraging steel, glassfibers, basaltic fibers or select polymers for the drums.

On earth, dual cylinder O'Neill type stations were originally designed to be solar powered, using large windows in their walls to reflect light in.
The tigers civilization did have the beginnings of workable fusion reactors when they started to design the template for their equivalent to earths O'Neill stations.
They also had excellent LED and EL type light sources, so they never contemplated to design their space stations with large windows, aside of a few experimental designs like Tiwaz station, in favour of solid metal walls and internal lighting.

The dual drum setup is contra-rotating to cancel out, or actively control, gyroscopic or vibratory effects, such as precession in a an orbiting setup.

Simplified size classes
50m diameter, 200m length : Homestead / Garden
250m diameter, 1km length : Hamlet / Park
500m diameter, 3km length : Village / Refuge
1km diameter, 5km length : Town / Sanctuary
1,5km diameter, 10km length : City / Biome
2km diameter, 20km length: Island
3km diameter, 50km length: Archipelago
4km diameter, 100km length: Peninsula
5km diameter, 160km length: Continent
Anything larger: Planet

There are many habitats that are shorter whilst having a larger diameter.
The length is more relevant to its classification than its diameter.
But the diameter is most relevant to the considered comfort, as larger diameters mean that you can see less of the opposite side of the drum.
An island class habitat with 30km length and 8km diameter is so large that it can afford a complex lighting system and artificial magnetic field on its inside as to allow bees navigating after the sun and pidgeons to navigate after the magnetic field

https://www.youtube.com/watch?v=gTDlSORhI-k