Tektro R540 brake caliper
It's a brake caliper! For stopping!
• dual-pivot design w/ forged aluminum arms
• quick release
• recessed nut
• adjustable angle cartridge pads
• sold individually - front or rear
• reach: 39-51mm
• colors: black, silver
• weight: 164g
Must be used in conjunction with a brake lever and cable. Don't try squeezing it with your hand!