Pallo Steamy Wanda (6mm)
Pallo 6mm Steam Wand Brush "Steamy Wanda"
6mm Diameter Steam Wand Brush Head for small diameter steam wand pipes around 6mm in diameter, but will fit even smaller home espresso machine steam wands as well.
Commercial espresso machine steam wands come in two sizes basically and will be either 7mm diameter or 8 mm diameter. As the bristles flex and should be tight against the steam wand walls, get the brush you know will fit tight.