without getting too much into it , blue parts and grey are some of the slowest selling colors we have related to any/all parts
hoses, brakes, anodized parts, you name it
I've had literally one person interested in blue and now one for grey, that would leave me with nearly 99 sets of 4 of each color on the shelf lol (no thanks)
We're selling through the red so fast there really is no need for another color but I'm making some black for folks not wanting red