Ergonomic and lock-on grips for numb-hand relief.
Numb or tingly hands are the most common complaint on e-bikes, because upright positions put more weight on the palms and less on the arms. Ergonomic grips with a flat wing spread the pressure across the hand and fix it for a lot of riders. Grips also wear out, get slippery, or spin on the bar, and on bikes with a twist throttle the stock grip on that side is a specific shorter length. They also matter for safety: a grip that rotates under a hard brake pull or in the rain is a crash waiting to happen.
Almost all flat and riser bars are 22.2mm at the grip, so any standard grip fits. The choices are lock-on (a collar bolts the grip to the bar, no slipping) versus slip-on (glued or pushed on), length (standard around 130mm, short around 90mm for the throttle side), and shape (round, ergonomic wing, with or without bar ends). Lock-on grips are the easiest to install and remove and never rotate in the rain. Ergonomic wings work best when they are rotated so your wrist stays neutral, which is easy to fine-tune with lock-on designs and fiddly with glued slip-ons.
If your bike has a half-twist throttle, you need one short grip for that side; many grip sets are sold in throttle-friendly pairs with one long and one short. Confirm your throttle type and bar diameter on your bike before ordering. Because grips are cheap, it is worth trying a pair before assuming you need a new bar or stem to fix hand numbness; many riders find grips alone solve it.