Yellow check in and check out pole and blue card balance reader

The yellow check-in poles can be found on the platforms where both the metro and trains stop and at metro stops where there are no gates (metro 51, Amstelveen route).  
The blue card balance readers can be found at all metro stations and metro stops. 

The yellow check in and check out pole

 Hold your ticket in front of the red OV-chipkaart logo on the pole, as shown in the photo. If you are checked in, the pole will check you out. If you have not yet checked in, the pole will check you in. The ticket reader display shows the remaining balance for each travel product on your personal or anonymous ticket.

The blue card balance reader

 Hold your ticket in front of this reader and it will display the remaining balance on your ticket.