Sliding Window Roller ID

I have an aluminum sliding window and it needs two (2) new rollers and a plastic assembly with screws) for the rollers. The plastic assembly is black in color with two screw holes (one at either end of the plastic assembly) for attaching to the underside of the sliding window. There are two grooved rollers that snap into the plastic assembly. The dimensions of the plastic assemblies are 2 in. long x 1/4 in. wide and 3/4 in. in height. I have a picture (below) of the roller assembly. Hope you can help!! Thanks