In rock climbing, as in bungee jumping and scuba diving, the proper equipment can make the difference between life and death. If you are new to the sport, you may be surprised at the variety of gear that climbers use, with names such as carabiner, ascender, sling, harness, nut, hex, cam, spring-loaded camming device (SLCD), and figure eight. The Air Traffic Controller (ATC), named after its main manufacturer, is a passive belay device. And of course there’s stuff like helmets, rope, and climbing shoes. An advanced vertical rock climber can look like a Christmas tree when all loaded up for a climb. The good news is you can find an enormous variety of new and used equipment for sale on eBay if your equipment collection needs a jump-start. If you need climbing shoes, buy them a size or two smaller than street shoes to increase sensitivity and prevent slipping. Cams, nuts, hexes, and SLCDs are used as anchors instead of pitons, which have fallen out of favor due to the damage they cause in the rock. And of course your first investment, whether you’re climbing the rock wall at the gym or El Capitan, will be a good climbing helmet.