Abstract: A line-drawing method for a sports field comprises: the foundation projection line-drawing device obtaining court options input by a user, and obtaining a court size and court shape according to the court options; scanning a pre-projection site to determine the safety of the pre-projection site; if the pre-projection site is safe, using the current pre-projection site as a target projection site, and turning on a laser unit according to the court size and the court shape to form a virtual court, and projecting the virtual court on the target projection site. This method can be used in the field lines of sports ball games. It can frame functional areas, replacing traditional marking lines and rope frame lines. It is more flexible and practical than fixed marking lines. It is strong, and it also solves the disadvantages of the site rope being unsafe, and being blown by the wind.

Abstract: A multifunctional tennis net, comprising a pair of nets, wherein the pair of nets are arranged side by side or in a vertical direction, the pair of nets comprises two independent meshes which are bonded by Velcro. The upper and lower sides of the nets are provided with second connecting pipes, and the left and right sides of the nets are provided with first connecting pipes. The bottom of the first connecting pipes are movably inserted with a bracket, and the outer wall of the first connecting pipes are sleeved with T-shaped sleeves and Z-shaped sleeves. The first connecting pipes are movably plugged with the second connecting pipes through the T-shaped sleeves, the first connecting pipes are movably plugged with the brackets through the Z-shaped sleeves, and the T-shaped sleeves and the Z-shaped sleeves are provided with positioning holes.

Abstract: A portable ball practice rack that comprises an inflatable ring, an outer wall of it is arranged with an inflatable and exhaust gas-proof interface; a protective bag has the same structure as the inflatable ring, and is sleeved on an outer side of the inflatable ring; and an elastic cover arranged on an inner side of an opening of the protective bag, and fixed to the protective bag by a connecting piece. The disclosure adopts the principle of inflating the inflatable ring to increase the size, after the inflatable ring is full of air, tighten the elastic cover. When storing, just discharge the air of the inflatable ring, the extremely small volume is convenient for transportation and storage. At the same time, the matching protective bag can effectively protect the inflatable ring from friction with the ground, which enhances the explosion-proof and protective performance of the inflatable ring.