Tool Review posts
I finally had the time to read all of Terry's tool review posts.
Fins - for those of us with very rigid ankles, fins can help with flexibility. I find fins useful for swimming slower, oddly enough. Going in slow motion to work through a timing issue is easier with the Zoomers on.
Kickboards - I certainly got injured from kickboards, back when I was just getting into swimming. My neck hurt from holding my head up and my shoulders hurt from holding the thing out in front of me. Much easier on the body to do the Active Balance drills with the arms at the sides.
Paddles - the type that are shaped like the hull of of a boat and intended to work the opposite of normal flat paddles (such as the Hungarian Tecnoc) are a longer-lived alternative to Fistgloves. I've injured myself with the flat ones, but can use the Tecnoc paddles for entire swims and feel they've improved my catch.
Pull buoys - As near as I can tell from observing people who use them, pull buoys mainly teach people to kick from the knees. Most people who use them kick anyway.... from the knees.
Snorkel - I find this useful from time to time. Such as when I wake up with a crick in my neck and it hurts to turn my head. Or I'm doing body dolphins and can't tell if I'm going too deep - the snorkel provides instant feedback.