Cokin P-Series Gradual Neutral Grey G2 Medium (ND4) 0.6 P121M(ND4) -0.6 P121M
Cokin Filter  P Series Grad. Neutral Gray G2 Medium (ND4) (0.6)  Filter.  Progressive graduation from the middle to the top of the filter, same color than 121 but lower tone. Only ND4 gradual filter.