@Helsi is correct. At one of our long-term rentals, a visiting relative of one of our tenants brought bed bugs. The apartment was chemically treated by a professional company three times and the problem was not solved.
After contacting another professional company that specialized in heat treatment and getting a quote, we decided to purchase the equipment, a tax deductible expense, and do it ourselves. One treatment and no more bed bugs. The equipment cost about $200 more than the quote for having the work done.
We now have the equipment if we ever need it and have loaned it to a landlord friend who also had a bed bug infestation in one of his apartments.
Search for Convectex if interested.