Heart-Gard Chest Protector for baseball players?

My little guys (5 and 7) are playing baseball this year. An optional piece of equipment is this Heart-Gard. I've never heard of it. I played baseball for years, my brother has coached T-ball and Coaches his son's Pony League team (13 - 14 year olds) and he didn't know anything about it.

I'm all for safety but I also don't want my kids to fear having fun unless they're surrounded by bubble-wrap. Would this be worn when playing pitch-catch? During practice/games? My thought is aluminum bats are the root cause for more injuries than the baseballs to the heart. I'd appreciate comments from anyone who has any experience or information with this.

Markwort Heart-Gard Heart Protector | Softball.com