Size: Diameter: 394mm / 15.5", Simply measure the inner diameter of the lampshade to determine the diffuser size required(Please carefully confirm the Size of the lampshade before purchase). Advantages: Made of 0.11 inch (2.7 mm) thick DOUBLE SIDED double smooth white acrylic. this diffuser is thicker than other diffuser and can withstand the heat generated by the lamp. It has good light transmittance, durability, heat resistance, and long service life. Application: This diffuser can soften and diffuse the light of light bulbs, making it perfect for eliminating glare from CFL or LED bulbs, improving visual comfort, creating more comfortable, softer, and even lighting, protecting your eyes, and creating a pleasant and comfortable reading and working atmosphere for your living space. In addition, it also adds a clean and tidy appearance to many types of lighting fixtures. Multipurpose: This lampshade diffuser is easy to install and only needs to be placed on the bottom ring of the lampshade. In addition, it is widely used in DIY lighting projects. Just drill a hole yourself and you can install it on the top or bottom of the lampshade of a desk lamp, floor lamp, or hanging drum-shaped pendant light, using it to guide light for focused illumination or improve reading lighting. NOTE: 1. Please tear off the transparent protective film of the product before installation. 2. This diffuser sheet does not have a pre-drilled center hole.