What timer do you recommend?

Any standard outlet timer will work. Here are two options our customers have used successfully:

*https://www.amazon.com/Techbee-Countdown-Programmalbe-Electrical-Appliances/dp/B086DN9QT3/?th=1

*https://www.amazon.com/gp/product/B0B6VPH24K/?th=1

We are not affiliated with these brands. The smart outlet option also lets you control the concentrator from your phone or an Alexa device, which some users prefer.