Goody Spin Pin is a pair of super imposable (FYI for the storage-obsessed) double coil wire with frosted paint texture and two balls attached to the ends. They are slightly thicker and around half the length of my middle finger (unless your fingers are exactly like mine, this is a completely useless piece of information), so they are fairly easy to carry inside pocket and makeup bag. There are two tinted version available, blonde and brunette (the shade I have picked up). Unless your hair is too thin to cover the pin up, the shade shouldn't matter that much.
The pin, which is not even that heavy for its size (maybe the wire is hollow), is inserted into the base of the bun easily and the metal balls makes the insertion pain and fuzz-free. I usually just twist my pin-straight Asian hair into a bun near the crown area, insert pin one and two in an interlocking fashion (which will prolong the hold for a teeny bit)...That would guarantee for an hour-long wear, if I remain stationery. If any physical activities is involved, like biking or walking, the hold will reduced to half an hour.
Forget about romantic bun at the nape (because it will collapse right away), a tight one at the crown is the only way to go, since I need the bun to be partially supported by my head/gravity. I find that when I used it with a rubber band (then poke the pins through the tied band), I do get a slightly longer wear but that just defeats the purpose, as I only bought this pair of squiggly metals so that I don't have to tie my hair up. (I mean, I can do a perfectly secure bun with a just a rubber band anyway...)
Overall: Very comfortable and seems perfect for shower time, it just doesn't work the way it claims on my hair type. I guess if your hair is finer or wavier this might holds better with the help of some friction. I am not a fan of the 6-7dollars price tag either, since this is essentially just wire ...I understand that we need to pay for the brain juice component but at the same time but wouldn't 3-4 dollars be more reasonable, consider similar squiggly pin sales for 1 yuan ( less than 20 US pennies) in China...