And all i can say is WOW!!These things are much better than Maxell XLII-S and TDK SA-X,they blow both of those tapes away in every respect.Much more natural sounding,deeper bass and much more natural highs,not tinny sounding like the Maxell and TDK on the high end.Really don't know if that white thing in the guide block does anything but it looks cool.Now if i could only find some place that still caries some Sony Metal Master cassette's i will be really happy!!PEACE....