What is a 4-person 30-second single and double shake relay?

4×30 seconds single and double shaking relay skipping: Four athletes stand in numerical order according to the ground signs of the competition venue, and with the 30-second password as the signal, relay skipping is performed according to the order of 30 seconds single and double shaking skipping by the first two athletes and 30 seconds double shaking skipping by the last two athletes, and the skipping times of each athlete are counted cumulatively.

According to different manufacturers, the dual Tik Tok system is also divided into a variety of structural patents. The most famous is Floyd Rose vibrato system, which was produced in the United States in the early days, and later changed to Schaller company in Germany, and later authorized Gotoh company in Japan and South Korea to collect licensing fees.

Freudian rose vibrato system;

Edge vibrato system: Ibana Company has designed an improved version: Edge vibrato system based on Floyd Rose vibrato system. Edge has some originality in design, including more integration, precise tuning, better wrist support and improved support columns, which have formed Ibana's own intellectual property rights. For players, it is like an ergonomically improved Freudian rose, which can make more pull-ups and feel better.