Samus can extend the length of her Grapple Beam if the player presses Z, then up, down, and up on the control pad, then Z again or the A button. This input combination must be inputted between frames 8-39 of the grab (the part of the grab before the grapple becomes visible).
If successful, the Grapple Beam will extend to approximately 3 times its normal length. It can also home onto opponents by pressing L when she pulls it out. However, unlike the normal Grapple Beam, one needs to press A or Z when the tip of the beam is over the enemy in order to grab them. The grab range is also limited to the tip of the Grapple Beam. These effects will remain after doing the necessary inputs until Samus loses a stock.