Crimp couplings must be installed by a fully trained assembler with appropriate machinery. Always confirm crimp ODs & tolerances. 4S Fittings are used on EC525 (in sizes -12 to -32 Only), GH493 (in sizes -12 to -32 Only), FC736 (in sizes -12 to -32 Only), FC273B (in sizes -12 to -16 Only), FC254 (in sizes -12 to -32 Only), FC500 (sizes -12 to -24), EC415 (sizes -12 to -32), EC600 (in size -12 Only) & EC810 (in sizes -12 to -16 Only).