Ngc Ultra

help with a coin need info .3 Questions?
2004-S 25C Iowa Clad PR70 Ultra Cameo NGC
What does the CLAD part mean and why would they bother to describe it?
Does it Add or subtract from the value?
thanks
The US mint made several varieties of state quarter dollars. Some are silver, but others are clad. All quarters in your pocket are clad; this means the center or core is copper sandwiched by two layers of nickel/copper. By the way “PR70 Ultra Cameo NGC” means this is a proof coin (mirror finish and not for circulation, and ultra cameo is an extra smooth finish) graded “perfect” by Numismatic Guaranty Corporation. These high grade coins are sought by collectors.
2009 Ultra High Relief, NGC Certified MS70 PL (Proof Like)