The English letters .R and .L on the headphones represent:

(1) L is light, which represents light music; R is rock, which represents rock. Therefore, when listening to light music, only wear the L one, and if you want to listen to rock music, wear the R one;

(2) LR means left and right. Bass and treble on both left and right earphones. I didn't make any mistakes (including those that were hard to hear) when I understood it from left to right. left means left and right means right.