Cover your HO scale tunnels with a random stone portal and color with Earth Colors™ Liquid Pigment.

Outside: 5 5/8 in W x 5 1/16 in H (14.2 cm x 12.8 cm) / 2 13/16 in W x 3 11/16 in H (7.14 cm x 9.36 cm)

Meets NMRA specifications