Shimano SL-DE21 is a rear shifter compatible with Deore RD-DE series derailleurs with an easy-to-grip lever for a secure and comfortable shifting action. The lever works best when paired with its matching Deore rear derailleur to ensure highly responsive and precise shifting. The SL-DE21 allows cyclists to effortlessly navigate different terrains and adjust their gearing to suit various riding conditions. With this shifter, riders can experience smooth and efficient shifting for an enjoyable cycling experience.