How do you do the zip glitch?

How do you do the zip glitch?
The zip glitch is inconsistent (and requires a stable 60 FPS) but, if done correctly, it can be performed by following these steps:

Hold Block.
Wait for a window of 129–135 frames.
Slow walk forward or backward during a window of 4–10 frames.
Stop moving exactly on the 139th frame.

The zip glitch is inconsistent (and requires a stable 60 FPS) but, if done correctly, it can be performed by following these steps:
  1. Hold Block.
  2. Wait for a window of 129–135 frames.
  3. Slow walk forward or backward during a window of 4–10 frames.
  4. Stop moving exactly on the 139th frame.