Electric collar recomendation that locks shock

I'm looking for an e-collar that can lock the shock, but keep the tone/vibration on at all times. I can't find anything online that specifically mentions it (just that it locks) so looking for personal reccomendations. We've worked with a trainer and our dog is used to an e-collar, but we're looking to upgrade. We primarly use the tone/vibration and want to be sure we don't accidently hit the shock unless we need to. Not looking to get into a discussion on whether we should/should not use one, just looking for reccomendations.