In my opinion I do not like them.They are big and bulky and therefore easier to leave behind.They also require more wind/breath to blow them.I had an upper respiratory infection and could not blow enough to make it work.A FOX 40 had the same outcome.A whistle that did work and I recommend is the ACR whistle.It is a little smaller than the FOX micro and almost as loud.I tend to get bronchitis easily in winter so this is my go2 whistle....

BOATMAN
John