There are a few ways to find out what Keurig model you have.
One is by looking at the type of coffee pods that you use: if they're called "K-Cups," then it's likely a Keurig K-Select, B60 or K75 because those models only work with k cups. Another way to tell is by looking at the Keurig's model number or serial code, which can be found on its screen.