I went ahead and merged your two posts, pretty much the same question.
Ebay/Amazon will have lots that are universal... generally they are held on with an allen key or other similar type bolt. That and Google for 12x1.25 should find you some other ones that twist on. Other universal style ones will have different size adapters that will allow you to thread to 12x1.25
The one thing you may want to consider before you get a metal/chrome one is that they retain heat/cold for a while. So in the winter, near freezing it will be really cold for a while and then really hot in the summer.
Last edited by rambleon84; 02-12-2013 at 08:53 AM.