Have any of you ever tried the adaptil diffuser?

It's suppose to stop dogs from getting scared when theres planned fireworks going off (e.g. bonfire night or 4th July). You either plug it in or put it on their collar and it's suppose to let off a fragrance that helps calm them.

If any of you have tried could you please let me know if they work. Or if anyone knows were you get them at a reasonable price. Charley and Buddy are pretified when theres fireworks going off so I want to make it easier for them.