I also have a QH10 as noted below. It works well. I've found that the latest Tarter box blade fits it as well as LandPride. My older King Kutter rear blade won't. Planning to sell the King Kutter that and pickup a compatible LandPrive blade.
I bought one a few weeks ago and it works very well. It is made by Tarter. TSC had both country line and Tarter and I understand they’re both made in Kentucky. I think king cutter is a different company.
I researched and searched and never could find conclusive information. I even called Tarter and asked if they were Land Pride QH compatible. Their phone reps didn't think their box blade would work with the QH10 since it doesn't have the adjustable top link section. I took a chance anyway...