Bos (2008) Type 2.3.1.1 = Disc fibula with central glass enamel and hubcap-like design with 6 holes
Literature:
Definition des Fibeltyps:
J. M. Bos, Medieval brooches from the Dutch province of Friesland (Frisia). A regional perspective on the Wijnaldum brooches. Part II: Disc brooches. Palaeohistoria 49/50, 2007/2008, 709–793.
This "wheel fibula" is also a "disc fibula with central glass flow and 6 holes, Bos (2008) type 2.3.1.1". Bos' type definition is much clearer because there are so-called "wheel fibulas" with 6, 7 or 8 unperforated pits or holes.