As examined in Lines et al study (5, 8), there are many different dog shock collar models and three basic types: (A-B) the collar that responds to stimulus and (C) the collar that responds to remote activation.
PetAmenity No Barking Control Anti Bark Collar [BEST VALUE / 2018 MODEL], Rechargeable / Rainproof / Reflective / 7 Sensitivity / Beep / Vibrate / Safe Shock for Large to Small Dogs