their online catalog. I know the brand you are talking about and from what I remember they were just a kind of lower end gauge. Summit has a really good selection of cheaper end gauges and accessories for those, you may be able to get lucky and find one that will match. Otherwise it looks like you will need to fab something up. If that comes to that I would recommend either hitting up RadioShack or an equivelant electronics store.
Sorry to be so general but without pics, i am limited on advise without giving out wrong information. Good luck though.