This model of Global Door Controls is considered as a plain bearing full mortise single acting spring hinge. It's highly recommended for use on commercial and residential door applications. Moreover, it's advised for use where automatic self closing of a door is required. The knuckle hinge is adjustable and the spring tension can be increased or decreased by using adjusting tool included. For maximum versatility use three spring hinges on required opening. Full spring tension may not be required on all hinges but allows for greater adjustment. This type sized 4.5 x 4.5 in. comes with a squared radius in its corner, bundled with a fixed pin. Item is available in many finishes: Oil Rubbed Bronze, Bright Brass, Satin Brass, Brushed Chrome, Polished Chrome, and Prime Coat.