Moose 4 Towball 4 Bike Dual Arm RackThe Buzzrack Moose, a big strong fellow, solid and reliable, just what you need from a tow bar bike carrier. So whats the big deal about Moose? Its down to better design, better quality, better safety, overall ease of use. These carriers are supplied ready to go; no assembly work is required. The patented conical tow ball clamp fits onto all 50mm diameter tow balls, even the ones which dont meet BS standards with e. g. rough casting around the tow