Flower Head Diameter is about 10cm/4 inches. The backside is not plain, therse's an about 6mm stems on the back.
If you use them on Styrofoam ball, you will need glue or individual stems. And the flowers can be directly placed on plastic flower ball rack.
Generally it takes 9-20 days to USA for the standard shipping
They are thin silk flowers, it's for 100 flower heads only, there's no leaves, no stems.
They were widely used to make kissing balls, flower walls, also popular for DIY crafts