As most people know, Line 6 began its history modeling guitar amplifiers. First, with the dedicated recording device the POD and then with its own line of guitar amplifiers. Eventually, the company branched out into other modeling endeavors such as guitars and, of course, effects.
The original Line 6 effects pedals consisted of the DL-4 Delay Modeler, MM-4 Modulation Modeler, DM-4 Distortion Modeler, and FM-4 Frequency Modeler. Each of these pedals sport 4 different buttons for recalling patches, controlling the DL-4 looper, and so forth. Eventually, Line 6 released more "traditional" stomp boxes, the ToneCore line, which focuses on individual effects such as delay, compression, chorus, and distortion.
The most recent effects pedal from the Line 6 labs is the "M" series, currently consisting of the M5, M9, and M13. Each of these pedals consists of modules that can be configured to be pretty much any effect in the Line 6 arsenal. The M5 does one effect at a time, the M9 three, and the M13 four (also with dedicated displays for each effect).