routes.MapRoute(
    name: "SpecificAction",
    url: "{controller}/{action}/{id}-{id2}",
    defaults: new { controller = "Main", action = "SpecificAction", id = UrlParameter.Optional, id2 = UrlParameter.Optional }
);

routes.MapRoute(
    name: "DefaultNoParams",
    url: "{controller}/{action}/",
    defaults: new { controller = "Main", Action = "Index" },
    namespaces: new string[1] { "Project.Controllers" }
);

[HttpGet]
public ActionResult TheAction()
{

}

[HttpPost]
public ActionResult TheAction([ModelBinder(typeof(SpecificModelBinder))] SpecificModel model)
{

}

<a href="@Url.Action("TheAction", "Main")">The Action</a>

routes.MapRoute(
    name: "DefaultNoParams",
    url: "{controller}/{action}/",
    defaults: new { controller = "Main", Action = "Index" },
    namespaces: new string[1] { "Project.Controllers" }
);

routes.MapRoute(
    name: "SpecificAction",
    url: "{controller}/{action}/{id}-{id2}",
    defaults: new { controller = "Main", action = "SpecificAction", id = UrlParameter.Optional, id2 = UrlParameter.Optional }
);

<a href="@Url.Action("TheAction", "Main")">The Action</a>

<a href="/Main/TheAction">The Action</a>

routes.MapRoute(
            name: "SpecificAction",
            url: "{controller}/{action}/{id}-{id2}",
            defaults: new { controller = "Main", action = "SpecificAction",
            id = UrlParameter.Optional, id2 = UrlParameter.Optional }
    );