This is a vinyl ester flat fitting by the company Aickinstrut. This is a top quality fitting brand and this product is no exception. The 3/8" thick fitting is meant to be used with standard 3/8" size hardware. It measure about 3-1/4" each way from top to bottom. Shown here in illustration as used over a tee joint of Aickinstrut channel. Get quote on your channel fittings and accessories and save!