【Muti-purpose】Adjustable Mast to Mast Mounting Kit offers even more versatility, great for mounting torches,flagpoles,umbrellas,radio/tv antenna and other outdoor decor. | 【3 Kinds of assembly】The antenna mast clamp is great for mounting round pipe(pole) to another round pipe(pole), square railings to another square railings,or mounting round pipe(pole) to square railings.(The diameter range of round pipes is 1 - 1.8", the diameter range of square pipes is 0 - 1.8"). | 【V Jaw blocks more stable】Heavy duty mast mounting clamp uses jaw blocks with two long bolts(2.2 " in distance,5.49 " in length) to give a stronger install for ensuring the patio umbrella not slip down. | 【Sturdy construction】Antenna mast to mast clamp kits are made of strong,durable galvanized steel,durable and designed to safely hold your patio umbrella. | 【Easy to install and move】Outdoor Sun Umbrella Holder Comes with 2pcs small wrenches,no need other tools that attaches to most decks, balusters,railings,or pipe quickly and securely.