Heat Treated Onion Sets

I now only grow Heat Treated onion sets after being disappointed by getting numerous onions going to seed in the past,especially the red onions,but since moving to heat treated ones I rarely,if ever get a single one bolting.

Which heat treated varieties does everyone else grow if any ?

 

Stuttgarter Giant & Red Karmen - trying these for the first time this year, as well as Bedfordshire champion from seed !

 

Hi all
Well this will be my first attempt at growing onions have to buy them from the bazar in the village so they have some that are about 3/4 of an inch and some that are about one and a half inches wide so i presume they grow into bigger onions i know very little about onions any ideas
T & H

 

Red Baron from Marshalls. Excellent !