In Canada the only current hot carcass measurements being made in regard to grading include back fat and loin lean thickness, and hot carcass weight. This is mostly determined by a tool called the Destron probe (but some use a Hennessy probe) to measure reflected light of different wavelengths. Ultrasound is also a popular method of determining these characteristics. Currently there is no effective, non-invasive method of determining marbling. Ultrasound methods do not work because the fat distribution is so fine. Measuring fat firmness on a regular basis has become popular. This is done by physical determination through compression or penetration. An alternative approach is being used in Japan, which determines the fat melting point. Some relatively slow methods are successful at determining boar taint in meat. Research is being done to increase the effectiveness of this method.