The Stayput No.3 Round is 3cm in diameter, 18mm tall, and weighs 110gms.
This popular size is used, sometimes permanently, in confined spaces within arrangements and in specialised containers.
A heavy metal flower holder with pins is called a Pinwheel, Kenzan, Stay Put or Spiky Pin Frog. A kenzan is used in Japanese flower arranging techniques called Ikebana. An old style of expressing Ikebana is Rikka.