The best way to describe McMaster is to say that they carry everything you need to build anything. Items that you could normally only order through factory distributors, or materials that could only be ordered in large quantities, are easily available in any size and quantity, no matter how small. (No minimum order, either!) Their prices are excellent and they tend to only carry good merchandise. Amazingly, when I order stuff at 5:30 p.m., it arrives the next morning with their normal shipping. Their catalog has long been difficult to get because you had to be a reasonably sized business with a Dun and Bradstreet number and established credit to have them mail it to you. But now that they have added an online service, everyone can easily order from them with a credit card.
— Alexander Rose
Do not order here. Contact McMaster-Carr directly via the blue link above.
Two random pages out of the 3,400 page catalog, containing 350,000 items: