It's exactly that. A means of identifying a fellow "Dis-er". You can add your "Dis name" then laminate for further recognition. Making Luggage tags is another use.. Many use them for decorating their "Room Window" .
Attach them to your Lanyard, fannypack, etc
You want the "alien green" as far as the official color.. but the next color up is fine as well. Sometimes the LGMH are hard to find.. and I heard somewhere that Home Depot was phasing out the LGMH. or maybe it is the whole MH color system... probably because too many of us have been taking them for something OTHER than a "paint chip"