2 books, First Multipart Porcelain Insulators and Second a Value Guide by Elton Gish The Multipart Porcelain Insulator volume second edition has 379 pages is a comprehensive guide with line drawings of all Multipart Insulators known at the time, Also included in the book is a value guide of M-Numbers. The second book is the value guide for UNIPART and MULTIPART Porcelain Insulators both are 2008 editions and both are outstanding reference books...$45.00... Plus postage. Don't wait for a sale, it's not going to happen. ** REMEMBER No Buyers premium to pay!!!! NO Bidding!!!!