It is important to note that nowhere in the play does Miller ever mention what it is precisely that Willy Loman sells. In a sense, this is because Miller deliberately presents Willy as a kind of universal "everyman," in order to depict him as a type of worker that could stand for all workers who are downtrodden and hardpressed, whereas if he was linked with selling a particular item that would lessen the impact that his character had. The force of Willy's character lies in the way that he sacrifices his entire life for a dream that remains unsubstantial throughout the play, and only brings him mediocrity and failure. However, at various points, he refers to the allure of being a salesman, such as in the following speech when he explains to Howard in Act II how the example of Dave Singleman caused him to become a salesman:
And when I saw that, I realized that selling was the greatest career a man could want. ’Cause what could be more satisfying than to be able to go, at the age of eighty-four, into twenty or thirty different cities, and pick up a phone, and be remembered and loved and helped by so many different people?
What is important in this play therefore is not what Willy Loman sells, but the fact that he is a salesman. Salesmen by their very nature are at the mercy of the capitalist system that they believe in so strongly, and thus Willy acts as the perfect "everyman" figure to point towards the evils of living by a capitalist system where everything, even a man's life, has its economic value, and where success is equated with the money you can earn.
Willy Loman returns home carrying two heavy suitcases which contain samples of whatever merchandise it is that he is displaying to buyers for retailers and taking their orders. While it is not specified what kind of items he is selling, it would appear that he is having an increasingly hard time making a living because the demand for these things is declining. Willy is in a situation similar to that of two characters in David Mamet's marvelous play about salesmen, Glengarry Glen Ross. George Aaronow and Shelley Levene are both getting old and are in danger of losing their jobs because they are not "closing." The problem seems to be that the scam of selling so-called retirement property in Florida swamps and Arizona deserts for exorbitant prices sight-unseen is running out of steam because the public is getting wise. Willy Loman, George Aaronow, and Shelley Levene are all growing older and losing their charm, energy, and self-confidence at the same time that the merchandise they are selling is losing its appeal. Things are always changing in the business world. New products are always being produced and promoted. Competition among manufacturers and among retailers is fierce. Salesmen have to be adaptable and not get stuck trying to ride a dead horse. But this gets harder and harder to do as a man gets old and set in his ways. George Aaronow and Shelley Levene are like Willy in looking back at the days when they were young, ambitious, and successful.