We love this reusable filter. It's solid and well made.  Easy to use. Just a few pointers: 
1. Depending on your may have to remove the adapter. But once you remove it, that's it. You never have to do so again. 

2. Basically just fill to the top line and press the medium cup (middle) for a basic 8oz cup of coffee. Takes a few trial & error runs to get the coffee just how u like it (measurement wise) but this is the formula we ended up with and use everytime. There's only two lines so just fill to top and try the medium or large cup.... which saves the most coffee grounds.

Very easy to use.  Cleans up so easy.  Instructions are well written and easy to follow. Saves the environment from plastic k-pods. Keurig customer service is super Awesome!