5.3 pistons with valve reliefs?
 

I have a gen 3 5.3 lm7 engine and I just purchased a set of gen 4 5.3 pistons and rods. The pistons have valve reliefs. I was always under the assumption that the 5.3s came with smooth pistons or smooth/cupped

I did a search on here and other sites to find out more about these pistons but having a tuff time trying to find out more about them like which gm 5.3s did these particular pistons come in? Are there any benefits or non benefits to these?

Any information is much appreciated.

Gen 4 engines with variable valve timing had valve reliefs.