what is the difference

[buhl]

the difference in 5557cbkd than 5557cbkd8d photos look the same

[CPPAaron]

Good Morning,

They are both the same kit with the exception that the "8D" comes with an 8" dual power booster. Perfect for those tight areas that need the assist like a 9" single but instead of having a wide 9" booster the do the dual 8". They have about the same amount of power assist.