From the manufacturer

Add a flash of color to your handlebars. Alloy Bar End Plugs are precision engineered and machined using lightweight, durable 6061-T6 aluminum. They are compatible with mountain and road bike handlebars thanks to an expanding wedge that makes a secure fit for most inner bar diameters. Available in a variety of anodized color options that match Wolf Tooth headsets, stem caps, seatpost clamps, bolts, and more.

Compatibility

• Works with mountain and road bike handlebars. The expanding wedge makes a secure fit for most handlebar diameters.
• Compatible with handlebars measuring 18 mm to 21.5 mm inner diameter.
• Use 3 mm hex tool (not included) to secure bar end plugs. Tighten until snug; DO NOT OVERTIGHTEN.
  
  

Specifications

• Weight: 17 g for set of two
• Alloy plug diameter: 26.6mm
• Compatible handlebar inner diameter range: 18 mm - 21.5mm
• Material:  6061-T6 aluminum cap, black anodized 7075 aluminum bolt, glass-filled nylon expanding wedge
• Made in the USA