It’s never a good idea to leave home without a charging cable for your smartphone, but who wants to have to have to untangle a cable that’s been rolling around in the bottom of their bag all day? That’s not something you need to worry about if you have a ChargeCard.

This credit card-sized micro USB cable slips right into your wallet, ensuring you always have a charging cable with you wherever you go that never gets tangled or broken. And thanks to Cult of Android deals, you can get yours for just $24.99 for a limited time — that’s 21% off its usual price.

Back in September, British carrier O2 teamed up with HTC and started an initiative to reduce the number of unwanted smartphone chargers in the United Kingdom. The carrier estimated that around 70% of handset buyers already had a charger that would be compatible with their new device, and so it started selling certain HTC devices without them.

O2 is now reporting that the initiative has been a big success. 82% of customers didn’t need to purchase a charger with their smartphone, the company claims, which surpasses its initial expectations for the effort.