Been a long while since I messed around with unity/vrchat so excuse the simple question. I have a model that comes with 4 textures; an albedo, a normal, a specular, and a roughness. I can see where the albedo/normal goes into the material slots...but I'm a bit confused with specular and roughness.

If I set the material shader to standard (roughness setup) then it lets me plug in the roughness texture, but it has no slot for specular, likewise the other way around if I use a specular setup. I honestly completely forgot what specular/roughness textures even do on the model? am I not supposed to use both at once or do I pick one or the other? if so which one should I be using