I use a small and a medium. One thing to note is that the smaller collars will come apart easier with a hard correction, or if the dog bolts. I recommend using a backup collar in addition to the prong, particularly with a reactive dog outside on a walk.
Nice pictures Maggie!
When a dog saves the life of a man, it becomes clear that partnership knows no bounds.
Fama - T.E.D.D. OEF XI-XII (GSD)(RET)
Marshall - T.E.D.D. OEF XII-XIII (Lab)(SF EDD)
Lucian - Med Alert / Mobility SD (Cane Corso)
Pud - the old man (Pit x Lab)