This is a model of the back spider from the Homecoming movie that can be applied to the back of your costume.
The spider comes in 2 different sizes, which size you need depends on your height:
Size S - if you are 5’9 (175cm) or shorter.
Size L - if you are taller than 5’9 (175cm).
The model comes in red color, but it is recommended to paint the model with a more vibrant red color that matches your suit.