U. S. Pony Express riders were issued a water sack, a horn, a revolver and which other item?

With the items mentioned, the Pony Express riders were also issued a Bible. The riders used a backpack (mochila) that could hold 20 pounds of mail along with 20 pounds of other material to be carried on horseback. Included in the other 20 pounds were a water sack, a Bible, a horn for alerting the relay station master to prepare the next horse, and a revolver. Eventually, everything except one revolver and a water sack was removed, allowing for a total of 165 pounds on the horse's back. Riders, who could not weigh over 125 pounds, changed about every 75–100 miles and rode day and night.

It was the job of the Pony Express as a mail service to deliver messages, mail, newspapers, and small packages from St. Joseph, Missouri, across the Great Plains, over the Rocky Mountains and the Sierra Nevada to Sacramento, California by horseback, using a series of relay stations. During its 19 months of operation, it reduced the time for messages to travel between the Atlantic and Pacific coasts to about 10 days. From April 1860 to October 1861, it became the West's most direct means of east to west communication before the telegraph was established.

Today, as part of its legacy, the United States Postal Service has trademarked "Pony Express" along with "Air Mail".