KNOTT Cast Coupling Head – 3000kg Capacity – 575005 – 50mm Ball Hitch. KNOTT Avonride Cast Coupling Head – 3000kg Capacity – 575005. Fits couplings with a 50mm dia. Supplied with 1xM14 & 1xM12 bolts, locking nuts & bolt head covers & lock. 50mm Ball Hitch for our Fuel Bowsers see MN100304. Good stocks available, …