Measure the product and state its dimensions in the description; a photo prop is only a visual aid. If you use a ruler or familiar object for scale, place it beside the item in the same plane and identify it clearly.
Keep the camera square to the product when possible, since perspective can make the near edge look larger. Avoid wide-angle distortion and include a separate full view so the scale reference does not obscure the shape or detail.
Use consistent measurements for comparable variants and check that the image and text describe the same size. Do not imply an exact dimension from a photograph alone. For unusually small items, give a close-up and a measured value rather than asking buyers to estimate from the screen. Use the same measurement units in the image and description.
