Fastens with press studs. As shown in the photos, the back side of the duvet has two seams as it's been made from a couple of different pieces.  This doesn't look strange though, not sure you would really notice.  

Material is in good condition. Feels like a cotton / polyester blend.  

Measures 132cm wide x 185cm long. 

Listing lots of other items including other vintage bedding so please check them out. Happy to combine postage on multiple items.