Sbp Centerlines

Did not know that thx,I was told that was what they were,they are very light,
Quite common. Kind of like "Bandaid" is used when someone wants a bandage, or "Kleenex" for tissue, etc.
Also, the two halves are siliconed where they meet.
I have a pair of 15 X 8.5 Centerlines, they weigh 14# each, if that helps you. But I'm pretty sure what you have is not a CL.