#1
Ones to avoid: any Ibanez RG that has a locking trem under the 1570 model.

This quote is taken from the ultimate guitar sticky and I would like to know, what it means. What is a locking trem under the 1570 model?
I'm really considering buying an Ibanez guitar. How do I know, if my target has a locking trem under the 1570 model?
#2
All the ones below the RG1570 come with an Edge III which is a pretty bad trem.