Comparison : Item # FME4, Merlin Marine Turbocharger; 6"W x 16.5"L
Item # FME4/7SP, Merlin Marine Turbocharger; 7"W x16.52"L
Item # FME4B, Merlin Marine Turbocharger; 6"W x 19.5"L
Item # FME6/9, Merlin Marine Turbocharger; 6"W x 25"L
Item # FME7, Merlin Marine Turbocharger; 9"W x 29"L