| Machine Bits | 1472 |
| Machine Bolts | 1420 |
| Machines, Blasting | 1500 |
| Machines, Boring | 1472 |
| Magnetos, Heavy Duty | 351 |
| Magneto Telephones | 83 |
| Magneto Testing Set | 104 |
| Magnet Wire | 1317 |
| Malleable Shields | 1425 |
| Mandrel, Casing | 366 |
| Manhole Skids | 1447 |
| Marine Fittings | 1124 |
| Marine Fixtures | 755 |
| Marine Horn | 356 |
| Marine Spark Coils | 347 |
| Marlin Cable Hangers | 1427 |
| Mast Arm Pulleys | 779 |
| Mast Arms | 772, 801 |
| Mast Arms, Cutter | 772 |
| Master Vibrator | 346 |
| Mats, Motor Car | 395 |
| Mats, Wood | 870, 1008 |
| Matting, Rubber | 822 |
| Mattocks | 1442 |
| Mazdaarcs, Cutter | 773 |
| Mazda Lamps | 627, 684, 689 |
| Mazda Lamps, Gas Filled | 689 |
| Mazda Lamps, Type C | 684 |
| Mazda Miniature Lamps | 632 |
| Measures, Tape | 1496 |
| Measuring Outfit | 1497 |
| Mechanical Rectifiers | 360 |
| Mechanical Signaling Systems | 69 |
| Medical Batteries | 544 |
| Melting Pots | 1493 |
| Mercury Arc Rectifiers | 362 |
| Messenger Clamps | 1418, 1455 |
| Messenger Clamps, Dicke | 1455 |
| Messenger Supports | 1418 |
| Metal Molding Clamps | 1084 |
| Metal Molding Fittings | 1083 |
| Metal Reflectors, Hubbell | 699 |
| Metal Reflectors, Ivanhoe | 798 |
| Meters, A.C. Watthour | 298 |
| Meters, Ampere-Hour | 292 |
| Meters, Frequency | 280, 312 |
| Meters, Graphic | 306 |
| Meters, Lamp Testing | 315 |
| Meters, Pocket | 341 |
| Meters, Polyphase Watthour | 303 |
| Meters, Portable Watthour | 297, 305 |
| Meters, Power Factor | 285 |
| Meters, Prepayment | 308 |
| Meters, Switchboard Watthour | 295, 304 |
| Meters, Watthour | 293, 299 |
| Meters, Watthour Demand | 301 |
| Meters, Wire | 1498 |
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| Metropolitan Cable Clips | 1427 |
| Mica Cloth | 818 |
| Mica Condensers | 327 |
| Mica, Cut | 821 |
| Mica Decorative Sockets, P and S | 970 |
| Mica Fuses | 99 |
| Mica Paper | 819 |
| Mica Plates | 817 |
| Mica Pockets | 1134 |
| Micas, Protector | 102 |
| Mica Tubing | 820 |
| Mica Uncut | 822 |
| Mica Washers | 820 |
| Micrometer Calipers | 1498 |
| Mil-Ammeters | 270, 273, 286 |
| Mil-Ammeters, Portable | 273 |
| Mil-Ammeters, Single Range | 287 |
| Mill Clusters | 691 |
| Millivoltmeters | 266, 287 |
| Millivoltmeters, Recording | 337 |
| Milonite Nails | 1147 |
| Mine Insulators | 1339 |
| Mine Rescue Equipment | 91 |
| Miniature Ammeters | 290 |
| Miniature Mazda Lamps | 632 |
| Miniature Receptacles | 857 |
| Miniature Sockets | 857 |
| Miniature Voltmeter | 290 |
| Mining and Park Cable | 1306 |
| Mogul Base Sockets | 950, 978 |
| Mogul Porcelain Sockets | 843 |
| Mogul Receptacles | 950 |
| Mogul Sockets | 843, 847, 950, 978 |
| Molding Couplings | 1084 |
| Molding Cross | 1073 |
| Molding Tee | 1073 |
| Monkey Wrenches | 1475 |
| Motor Attachments | 131 |
| Motor Car Mat | 395 |
| Motorcycle Horns | 354 |
| Motorcycle Lighting Outfits | 393 |
| Motorcycle Lights | 389 |
| Motorcycle Spark Coils | 348 |
| Motors, A.C | 106 |
| Motors, A.C., Mill Type | 113 |
| Motors, Adjustable Speed | 140 |
| Motors, Crane and Hoist | 123 |
| Motors, D.C | 120 |
| Motors, Display | 657 |
| Motors, Sewing Machine | 587 |
| Motors, Single Phase | 106 |
| Motors, Small Power, D.C | 120 |
| Motors, Three Phase, Two Phase | 109 |
| Motors, Variable Speed | 123 |
| Moulding, Wire Grip | 1092 |
| Moving Picture Machine Cable | 1308 |
| Multiple Batteries | 400 |
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