Since I was PM'd by a fellow MCM member asking advice and info about locks etc thought I may as well throw some info here to share... even though this thread is primarily about GPS trackers. Of note it is worth reviewing the information to motorcyclists from a thief see bottom of this post for link.

Kryptonite locks. Deemed solid offer a variety of locks. Worth looking at the companies website too. Kryptonite locks for sale on Taobao.
The Kryptonite prices vary a little on Taobao, but expect to pay around 2000 for the chain lock and about 1000+ for the U lock.

Look for the NYC fughetaboutit chain/lock from Kryptonite

There are also Xena XUL310 U locks which incorporate an alarm 110dB. So plenty loud. The Xena locks are n Taobao but not specifically the XUL310.

Advice:
Use a combination of two locks, a U lock and a chain lock. The U lock through one wheel to the frame while the chain lock to the other end of the bike and through a solid object/ground anchor.

Also there are chain locks at my local B&Q, 289 kuai. Masterlock I think is the name, I use one on my Dragstar 1100 Classic, in combination with a disc lock.

Worth a read:
ask-a-motorcycle-thief