What is Ag4/Ag5 and Ag7

What is Ag4/Ag5 and Ag7
here we will know about ag4 grinder machine, angle grinder 7 machine,
#what is ag7, # Anglegrinder5, #Disc, #Ag9 cutting wheel, #Grinding disc,#Grinding, #cutting, #metal cutting, #metal grinding
# • Pcv/psv/pvrv/prv