Twelve South AirFly Pro

Whether you're using in-flight entertainment, gym equipment, or an older audio device, the AirFly Pro lets you use your wireless headphones without digging out a cable.

Pairing is straightforward, battery life is solid, and audio quality is more than adequate for travel. It's also compact enough to leave in your backpack without thinking about it.

The biggest downside is price. It's a niche accessory, and many people simply won't use it often enough to justify the cost. But if you travel frequently, it quickly becomes one of those gadgets you're glad you packed.