Airofit breathing trainer

[DehanL]

Has any cyclists or (dare I say it) triathletes tried the Airofit or similar respiratory trainer? Probably not for everyone, but perhaps useful for someone who does have some sort of issues with dyspnea.

To extend that- has anyone bought one and now no longer uses it? It seems like something that you get for Christmas, use twice and then leave in a random drawer. I'm hoping to buy one of from someone like this- then use also use it twice.

Thank you!