Use this fun, stackable model to explain the progression of cervical dilation and effacement. The ten removable rings depict each centimeter of dilation from 1 cm to 10 cm. The rings depicting 1 cm to 5 cm are blue, representing latent (early) labor, which is from 0 to 6 cm of dilation. To represent active labor, the rings from 6 cm to 8 cm are green, and the rings depicting 9 cm to 10 cm are pink to represent transition, which is from 8 to 10 cm. The varying thickness of the rings make them a useful tool for discussing effacement. Comes with protective carrying case. 5" x 2" x 5".