Stop in for a cup of coffee

Any HVAC guys here? I need to find just the ceramic insulators for the electrodes for a test set any ideas where to just buy those? 4 1/4 long, need four of them.
My family ran an HVAC business for 40 years before my grandfather retired. My brother is a licensed hvac tech still, I'll ask him but likely you'll have to either find an online dealer or a hvac distributor store