As far as features go, you have a few options. To be effective, the lightbulb needs to remain on for a designated period of time. Because of this, UV shoe sanitizers have timers (usually set in 15-minute increments) that allow for 2 or 3 different operating modes. Additionally, an on/off switch is desirable to help reduce the risk of accidentally turning on the unit before it’s inside the shoe. While some sanitizers have a side benefit of helping to dry damp shoes, in most instances this is not a primary function.