These are HKS inserts that can be used on the HKS SSQV blow-off valves. They fit into the "snout" replacing the stock insert and offering a different sound.
Gold: High-pitch Purple: Low-pitch
Genuine HKS products! Sold each/separately.
We found a video on Youtube that offers a comparison of the different sounds of the different inserts:HKS SSQV BOV Insert Comparison