ATC
An Air Traffic Controller, or ATC, is a popular belay device made by Black Diamond. It resembles the belay tube, but is slightly shorter. ATCs are popular among sport climbers for their simplicity, and light weight.
The Climbing Glossary - ATC

ATC
An Air Traffic Controller, or ATC, is a popular belay device made by Black Diamond. It resembles the belay tube, but is slightly shorter. ATCs are popular among sport climbers for their simplicity, and light weight.