For barbers who use trimmers all day long, this charging mat is maybe a killer app. This is a fade and line-up tool marketed at pros, but it is compatible with standard Wahl trimmer guards if you're not a free-hander. A nice set of guards is $40 from Wahl, assuming you don't have Wahl guards floating around your bathroom cabinet already. (Honestly, I've gotten oddly good at free-handing my beard without trimmer guards, and I get more precise results this way than with guards … but this requires faith, attentiveness, and a steady hand.) This corded outliner is the device old-school barbers have been trusting for edge work since the phrase was invented.