Using the symbol '-' in route will cause error

I want to route a URL like "http://localhost:3000/admin/product-
details".I defined the route mapping in routes.rb:

map.namespace :admin do |admin|
    # Directs /admin/products/* to Admin::ProductsController (app/
    admin.product_details '/product-details(.:format)',
                                :controller=>"product_details", :action=>"index",
    admin.connect '/product-details(.:format)',
                                :controller=>"product_details", :action=>"create",


When I visit the URL,Rails throw a error:
ActionController::RoutingError: No route matches "/admin/product-
details" with {}

I visit http://localhost:3000/admin/product_details well.

Can you not use an underscore?