Abstract: A variable fit fastener-applying attachment is disclosed which is particularly suited for use with a pair of locking vise type pliers. The attachment comprises a pair of first and second clamp members which are configured for respective mounting on the pliers jaws. The clamp members are configured for applying clamping pressure to a fastener assembly positioned therebetween such that the assembly is permanently applied to a piece of fabric, plastic, leather, or the like sheet material. In one embodiment of the invention, the variable fit nature of the attachment for mounting on different pairs of pliers having differently sized jaws is achieved by the provision of a pair of flexible gripping fins on each of the clamp members. In alternate embodiments, each clamp member is configured to provide resiliently flexible inward and outward movement of its sidewall portions to achieve the desired gripping engagement of the clamp members with the pliers jaws.