1. Adjustable Design: Fits up to 2-inch umbrella poles/off-set poles, with 4 locking knobs for diameter adjustment; securely mounts on square balcony railings, benches, etc. 2. Wind-Resistant & Stable: All-welded stainless steel construction with no breakage risk, enhancing stability to keep patio umbrellas from moving or rotating in wind. 3. Durable & Rustproof: Premium stainless steel with black coating for corrosion and rust resistance, ideal for deck and outdoor use with long service life. 4. Easy Installation: Quick-mount umbrella clamp with 8 self-tapping screws for firm attachment to wooden posts and other surfaces. 5. Space-Saving: Specially designed for deck railings, suitable for decks, bleachers, backboards, boats, fences, and other corners/surfaces to save floor space.