I had a service call from hell today, but thats not what this post is about. I had to change out a bunch of Orbit sprayheads (the ones that look like 2" pop RB Sprays) because they had cracked open. Originally I just figured it was because Orbit is garbage, but when I pulled the first one, I noticed it had a check valve. These heads were in a landscape on 2'-3' risers. My theory is that the check valve did not allow the heads to drain, and then it froze, and all the heads ruptured. So, if your in freezing territory, don't use SAM heads on risers.