Stone cage net protective structure is in itself under the action of gravity for the installation.
石笼网防护结构是在其本身重力的作用下进行安装的。
2
Gravity ball check valves are converted to vent valves by replacing the standard ball with a floater ball and inverting the valve at installation-with seat up.
The novel toy is simple durable, having easy installation. The wing position and a model gravity center can be adjusted to obtain more perfect flying state.