Casita III (2-sided)(Black Grassland 2) raising queen ants What does add a second

What does add a second side mean

White Interior/ LightBlue Exterior Color

1/2" connection port for connection to other habitats

The Stronghold formicarium is twice the exactly twice the size of the Fortress formicarium with double the nest space and two foraging areas

Gold Exterior/Sand Interior Color

Casita III (2-sided)(Black Grassland 2) raising queen ants What does add a second***Casita Type III *** For more information on this product, click this link. Features: Black Exterior Premium Grassland Foraging Area (+5) Medium Large tunnels and chambers 3 levels White Sand Interior 2 Nestmates 2 sides 2 water towers Add On Package Optional