Bought this knitted collar a few years ago (2008 if I'm not mistaken) in China. Didn't wear it often, maybe only twice. Maybe because it's knitted, making it seems like it's meant for winter. But thanks to the new trend lately, detachable collar is available everywhere! I haven't buy any detachable collar, though, sadly.
Dress, collar, legging - Unbranded
Socks - Sox Galeri
Shoes - Zara