This deluxe horsehair dusting brush is part of the best in breed cleaning series. The bristle fill is composed of natural materials for gentle cleaning and extended life. The opening is 1. 25" inside diameter. The softer PVC case that surrounds the bristles is pliable and designed to give when needed to better form to the hose coupling. The exterior material is also non-marring and wont scratch furniture or leave marks on the work. Fits standard vacuum connections at 1. 25" (32mm) friction fit. Typically works with central vacuum wands and canister vacuums.