Signal-Android/res/layout/contact_selection_recyclerview_header.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools"
          android:layout_width="@dimen/selection_item_header_width"
          android:layout_height="@dimen/selection_item_header_height"
          android:gravity="center"
          android:textColor="#666"
          android:textSize="22sp"
          tools:text="H" />