A Suspended 2nd chord is a triad where the third is replaced with the second. The chord contains the root, the second and its perfect fifth (I, II, V) as shown in the schematic above.
There can be multiple versions of each of these notes by fretting the same note
on different strings. Sometimes the same note is repeated, other times the note
is duplicated one octave higher.
In each case, though, the character of the chord is preserved.