Zerchers, Safety Bar

Can someone please describe how to perform Zercher Squats? Also, my friend told me about some sort of safety bar that attached to the barbell for squats. He told me it weighs 55 lbs. and relieves stress from the shoulders and makes the squat harder. What is this? Thanks.

just take a standard bar and craddle it in your arms so that it is in the crotch of your elbows in front of you against your lower chest and your forearms are crossed over the bar. Wow, I haven’t written a run on sentence like that since grad school. Sorry.