How do you date a Gillette safety razor?

Gillette Date Codes were used from January 1951 until 2001. They are found in the top left and right corners on the underside of razor guards, both 3 piece and 1 piece models. The letter represents the year, found on the chart below, and the number 1-4 correspond with the quarter of the year.

How do you adjust a safety razor?

3:395:13How To Use An Adjustable Safety Razor - YouTubeYouTube