In ancient times, compasses only had disks. Why can't you tell? The main reason is that there is no meridian. I usually pull one myself, and even my hand won't notice that it's crooked.
I have been using Jiyitang's compass, and I used Jinyutang's before. Now a few friends and I are using plates from Jiyitang. Good quality, accuracy and high cost performance. Every time they buy a compass, they give them some practical gadgets. I suggest you also have a look.
Taobao or Baidu search for medical clinic.