This listing is for 1 set of 2.5” Rollerblade Casters, which consists of 5 rollerblade casters. Floor friendly design makes it usable on hardwood and or carpet. Has a weight capacity of 650 which exceeds the minimum standard. These are universal caster, which fits on mostly all office chairs, except IKEA chairs. But as Chair Technician I have used these as upgrades and or replacements for the chairs you see in the pictures. Easy installation, but if you need help or need an installation link or video, just contact me, don’t be afraid to ask.