has anyone ever used one of these, an attachment to illuminate cross hairs

http://www.cabelas.com/cabelas/en/templates/product/standard-item.jhtml?id=0006715710061a&navAction=push&navCount=1&indexId=cat20758&podId=0006715&catalogCode=XD&parentId=cat20758&parentType=index&rid=&_DARGS=%2Fcabelas%2Fen%2Fcommon%2Fcatalog%2Fitem-link.jhtml.1_A&_DAV=MainCatcat20712&hasJS=true

seems a bit awkward/annoying but I don't know