Box 4 anchors on the scale's fourth degree — B at fret 7 in the worked example — and lives in the register where lead guitar starts to sing. Frets are physically closer together up here, string tension yields more per finger, and the two facts together make this the bending window.
The window, computed (E minor pentatonic)
| String | Frets | Notes |
|---|---|---|
| 6th string (E) | 7 / 10 | B / D |
| 5th string (A) | 7 / 10 | E / G |
| 4th string (D) | 7 / 9 | A / B |
| 3rd string (G) | 7 / 9 | D / E |
| 2nd string (B) | 8 / 10 | G / A |
| 1st string (E) | 7 / 10 | B / D |
Using it
The classic move of this box: bend its highest-string notes up into pitches from box 5 — a whole-step bend here lands exactly on the next scale tone, which the note column above lets you verify pitch by pitch. Phrases here sit an octave above box 1's register, so alternating between the two windows gives a solo its floors. As always, the overlap is the route: box 4's ceiling is box 5's floor. Full fingerings in the scale reference.