<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
     <item android:state_checked="false"
         android:drawable="@drawable/btn_check_small_off" />

     <item android:state_checked="true"
         android:drawable="@drawable/btn_check_small_on" />
</selector>