M Part Cycling Spt100 Threadless Shim Stem Adapter 1 18in 28 6mm 1in25 4mm Black 6 25 4, Black, O S UK

Amazon

A split aluminium shim that fits over a 25.4 mm (1 inch) steerer tube changing the outer dimension to 28.6 mm (1-1/8 inch) Allows the use of a stem designed to fit 1-1/8 inch steerer tubes where greater choice is available Black anodised finish with laser etched detail 1in - 1-1/8in (25.4mm - 28.6mm)

Blacks

A split aluminium shim that fits over a 25.4 mm (1 inch) steerer tube changing the outer dimension to 28.6 mm (1-1/8 inch)Allows the use of a stem designed to fit 1-1/8 inch steerer tubes where greater choice is availableBlack anodised finish with laser etched detail