This is a mounting accessories. Easy to transform the slip fitter mount to Arm mount for square pole.Very useful for LED shoebox light mounting. If you buy our LED shoebox light which is with slip fitter mount,but you need them to supply in the square pole,then you can buy this Adaptor together.very easy to install on square pole. The diameter is 2.3'', Size: Approx. L 8.66" x W 3.82" x H 4.07" Additional Details ------------------------------ Product description: This is a mounting accessories. Easy to transform the slip fitter mount to Arm mount for square pole.Very useful for LED shoebox light mounting. If you buy our LED shoebox light which is with slip fitter mount,but you need them to supply in the square pole,then you can buy this Adaptor together.very easy to install on square pole. The diameter is 2.3'', Size: Approx. L 8.66" x W 3.82" x H 4.07"