The perfect little pocket just big enough for your keys, phone, cash and some lip balm.  Clips onto your pouch (or mei tai, ring sling, wrap or buckle carrier) with a carabiner.  

Made by Hotslings, but works with other carriers as well. 

Use this long after your babywearing days are over, as an extra pouch in your purse. 

5"x6", with zipper closure. 

Ingenious!