BULLDOG wood connectors are used for the fastening with bolts.
Bulldog dowels as disc dowel types C1, C3 and C5 for two-sided dowels and as disc dowel types C2 and C4 for one-sided dowels are regulated in DIN 1052:2004-08
Their applications are for instance for frame corners, collar beams, coupling purlins and cross-grained wood joints.
One-sided versions are used for wood-steel and wood-wood-joints. The bolts must fit tightly to the ring bore surface. These take direct part in the force transmission. Two-sided BULLDOG wood connectors are used in wood-wood joints.