A colorful, square-shaped puzzle mat with a grid pattern is displayed. The mat has a vibrant color scheme with alternating rows of red, orange, yellow, green, blue, and purple. The mat is accompanied by a ruler with measurements in centimeters, indicating the mat's dimensions. The ruler is placed diagonally across the mat, with the zero point at the bottom left corner. The measurements are in Chinese characters, and the ruler is marked with '30cm' at the bottom right corner.