The wheel diameter is 60 mm, and the space between the two casters is 22 mm. I don't know if this lock will work properly, but I'm posting the design here. If your casters have different dimensions, just take inspiration from my design. I created it in 10 minutes in Tinkercad, so you can do it. My chair is SENSE7 Spellacaster,so if you have it too, you can take this file without reworking it.