Unlike the mainland China, the Hong Kong Police Force is allowed to purchase weapons and equipments from the United States manufacturers.
This means U.S.-based businesses are making money while HKPF assault the demonstrators using American weapons at the behest of Beijing.
The supplier of HKPF's tear gas canisters:
Combined Systems, Inc.
Jamestown, Pennsylvania
https://www.inquirer.com/business/hong-kong-protests-tear-gas-made-in-pennsylvania-20190811.html