How to systematically learn backstroke

What is backstroke?

Backstroke, also known as back swimming, is a swimming posture in which the human body is supine in the water. Backstroke includes anti-breast swimming and anti-climbing. Because the face is on the water, breathing is very convenient, but swimmer

Inkmaker automatic deployment system

The Prisma system is an automated ink compounding system for small and medium sized printing plants. This system allows the printer to deploy any color at any time. Based on a fully automatic and easy-to-use design, the operator can match colors according to the i