General Controls GC Co. Automatic Heating and Industrial Gas Controls Service Instruction Manual Revised 12-54. This book measures approx. 8-1/2" wide by 5-1/2" tall with 159 numbered pages of valuable information. The staples have rusted and no longer hold the cover, but so far the rest of the pages are stapled. Pages are yellowed, but still plenty readable. Flipping through the pages, I don't see any writing or highlighting on the inside pages. Although some of the information may be outdated, I see headlines like "checking thermocouple with millivolt meter" and exploded views of some of General Controls products would provide someone excellent resource information. Please look carefully at the fourth picture. It has the contents of the book. There is also an Index to the 72 products covered in the book.