Polarity (positive right / left)
Position of the positive terminal (+) viewed from the front of the battery with terminals away from the user. Defines mechanical fit.
Polarity defines on which side of the battery the positive terminal (+) sits. To determine it, look at the battery from the front, with the terminals on the side opposite to you and the label facing up: if the (+) is on the right it is right polarity (often marked "+R" or with code "0"); if on the left, left polarity ("+L" or "1"). Each car accepts ONE polarity — it is fixed by the length and position of the vehicle's cables. If you buy the wrong polarity you will NOT be able to connect it safely (the cables won't reach the correct terminal and forcing it can damage the vehicle's electrical circuit).
Many common capacities (60, 70, 80 Ah, etc.) are available in both polarities within the same product range; verify by looking at the original battery before buying. In motorcycles, marine and commercial vehicles there is more variability. If your old battery has (+) on a given side, the new one must match.