These freaking bobby pins are the best I've ever purchased. My female family members are impressed. I have thick, straight hair that weighs nearly 1.5+ lbs/0.68+ kg, yes I weighed it. You really don't know how much weight you're carrying around on your shoulders until you measure it out, I was very surprised. Japanese people tend to have thick hair (used to be a hair stylist, and have worked on multiple ethnic-specific hair), so I'm not surprised they made a version of bobby pins meant for thicker haired people. Pros: - the material is a hard metal mixed with something else, which makes it flexible but it snaps back into shape quite easily. (I remember reading it was iron mixed w/other things, I'm guessing a polymer that allows for flexibility?) - thick, it allows for more security - bumpy ridges help to keep them together when you criss cross them. - long, so it great for people with long hair - I have had some for so long that they no longer snap back into place, but despite this, if I use an old one with a non-bent one, it's still really sturdy and doesn't slip. - there are 300 of these!!!!! I don't have to buy 50 or 75 at a time from the drugstore anymore. - truly does not rust. Unless you're careless with constantly leaving it out with water, this won't be a problem. I've left them in showers for a few days before and no rust, altho, that did change after 1 month+. Cons: - slightly heavier metal will hurt after long-term use. I mean it, if secured well in place, the pins are right on your scalp. The weight of your hair + gravity + hours of wear = lots of pressure on one spot on your scalp. This is why I had my hair weighed, I was curious after taking down a bun one day and having to gently rub the sore scalp. - once lost, lost forever, but forever in my heart. - choking hazard. I feel like this doesn't need to be said, but please, please watch your little ones (human or otherwise), they're grabby and a lot can happen in 2 seconds. - may trigger TSA metal alarms. Let me explain, I had a small handful in pocket, and set off the metal detector alarm while I was checking in. The reason is because of the thicker material, and having a bunch, clumped together in your pockets will make it seem like you forgot to take your watch out of your pocket. I have since carried a tiny bundle of less than 7 and have not triggered any metal detector alarms since. - a little too sturdy. Every now and then when I'm in a rush but I need to adjust a few pins because they're pressing on a nerve or something, it's actually kind of difficult to pull them apart, the ridges are hooking onto each other too well. - pulled my hair out. These babies hold on tight, so be gentle in disentangling them from your hair. When you're not careful, it will pull out your hair, so don't yank.