There are several reasons for that:
1. Products like lasers, E-cigarettes cannot be shipped by express mail as it can be easily detained by the customs. In this case, we ship them by regular post service.

2. Some countries are not covered by UPS/DHL/Fedex, so the carrier will change the shipping method for your package. Countries that we can currently ship EMS packages to:
Australia, Austria, Belgium, Cambodia, Canada, Denmark, Finland, France, Germany, Greece, Hong Kong, Indonesia, Ireland, Italy, Japan, Luxembourg, Macau, Malaysia, Malta, Mongolia, New Zealand, North Korea, Norway, Papua New Guinea, Philippines, Portugal, Singapore, South Korea, Spain, Sweden, Switzerland, Thailand, U.K., U.S.A, and Vietnam.