Please keep in mind that not all clamps have the screws to receive a bracket such as this in the same place. This means it may not fit a clamp you have purchased elsewhere. That said, new holes can simply be drilled to accomodate the measurements (outlined below).
This attaches on to a clamp/other surface via two screws (usually supplied with a clamp). The measurements of the drip tray holder are as follows:
Drip Tray measurements:
The drip tray sits neatly into the bracket.