The Hakko 926 Soldering Station was replaced with the Hakko 936 Soldering Station, however both stations use 900 Series Tips. Depending on the iron you have with your station, you will use either 900L, 900M, or 900S tips.
If your iron has a small plastic retaining nut to hold the tip onto the iron, you are using a 900S iron and will need to use 900S Tips
If your iron has a series of holes in the metal enclosure near the metal nut that holds the tip onto the iron, you are using a 900L or 908 iron and will need to use 900L tips.
All other irons are 900M or 907 irons and use 900M tips.