No reviews, so I have no idea about the quality, but they're cheap. It's a glass, you put whisky in it, you drink it, then you chuck it on the dishwasher.
Shipped by Amazon, if they're shit, send it back.
Real Glencairns are double the price, so make up your own mind. I use cheap/free copitas personally.
This is going to take my Amazon pantry close to expiry Pepsi max to the next level.