Well how would your DP know if they work or not if he hasn't tried one out? We had one for DD when she turned 8mths and started teething and yes, I think it helped ALOT. At first we left it on only while she was awake but then someone said leave it on 24/7 and it really did help. I never liked using bonjela either (only once or twice) and mainly stuck to Brauers Teething Relief liquid and when really bad, panadol.

We only just took it off our DD only because she isn't teething anymore (still waiting for 2yr molars though - eeek ) and she broke it
That's what happened to our DD's too. I think I'm going to have to buy another as her whingeing has gotten worse. I was hoping we'd be right but her molars are pushing up. We got ours from sunshine n lollipops x