Naturehike Outdoor Survival Mini Aluminum Alloy Whistle w/ Keychain - Green

Pros: The whistle is Cheap, and compact, and is of a good quality, it is light and has no complicated mechanism which may break, and it's easy to use. and easy to carry around in a key chain and is hardly noticeable. The packaging is good.

Cons: The sound emitted by the whistle is too low even when you blow really hard, which is not good in an emergency situation.

Other: Overall good. Maybe a life saver in case of an emergency. To some up it's good for its price.

Pros: Lightweight, durable, compact, it won't get easily damaged or lost, and doesn't crack or melt if exposed to severe climate conditions (fire, impact, ice) - quite loud but most effective in a series of short bursts (a fairly short series of blows instead of 1 long blow)

Cons: Not as loud as it might need to be for certain survival situations (high wind / snow / noise area)

Other: Great quality at a good price, definitely worth having in case of emergencies. As the saying goes, better to be prepared than to be sorry.