This book is sized to be carried in the field while at the flea markets, antique shops or auctions.Inventory in the workbook is based off of the Ohio Tool Companies' Catalogue No. 23 (circa 1910)Keeping track of your collection is an important task in your collection. Although this workbook is written for your Ohio Tools collection, you can also use the extra spaces for other pieces in your collection.As the collection grows, you should keep track of the pieces you purchase. The information recorded can be used for future references for many reasons. Sometimes it's important information to know and sometimes it's just fun to remember. Also tracking what you have helps to fulfill a "set" or series within your collection. For instance it's good to know if you need one or two specific planes to complete a set of a particular type or style.There's certainly nothing wrong with having a few duplicates in your collection (some collectors strive for it), but purchasing something extra should be an informed decision and not something that happens accidentally. Otherwise, you're wasting money that could be spent on an entirely new item. Having to many of one particular size and type can quickly get out of hand. There are some planes that are just a lot more abundant than others and knowing what you have and what you need is important.