That Fox 40 Howler looks pretty nice, I wonder if and when it will get to Mexico.
I´m still partial to ACME, I have had some of them since the 60´s, the plastic thunderer with pea is still one of my favorites, the pea design allows much more variation in tone and volume (some people say the whistle talks), probably not too important for survival but useful for sports and traffic (Fox does make a couple of models with pea, check out their model for the NHL). The Storm (which is also recommended by Ritter) is a very good pea design, it is big though.
For pealess whistles my favorite is still the ACME 2000, with sides filed down it is very thin and carries fine in a neck lanyard under my shirt, I feel it is comparable in volume and pitch to the Fox 40 Classic (haven´t done any testing though).
I¨ve heard comments about high pitched pealess whistles not being too good for kids, the sound is painful to them and they stop blowing them, I don´t know if it is actually true, personally I think that a simple Acme pea design is right for kids and inexpensive, that is what I have given my daughter to take for her camping trips.
Here´s a link to the ACME site:
http://www.acmewhistles.co.uk/
Luis