Allen 20mm Flip Flop Block Select (See Table Below):AL-2123 20MM DYNAMIC: SINGLE FLIP FLOP - EACH part number BA21053

part number BA21053

Brand ASAP Electrical Amps 20A Voltage Up To 28V DC Length 46mm Width 28mm Depth 14mm Cut Out Required 9

whilst if you have the AK351 head (generally on the bigger trailers)

C218M2T is an OEM pack of 50

Allen 20mm Flip Flop Block Select (See Table Below):AL-2123 20MM DYNAMIC: SINGLE FLIP FLOP - EACH part number BA2105320mm Flip Flop Block. A 20mm ball bearing sheave riveted to a stainless steel frame which can move through 180 degrees. The body is fixed to the backing plate with a removable clevis pin for easy removal and installation. Spec Sheet Part Description Line Dia. mm Fixing Hole Centres mm Fixing Hole mm Max Working Load Kg Break Load Kg Weight gm RRP Inc VAT Unit AL 2123 Flip Flop Block 5 16 4 105 350 19 48. 40 EACH