Bass string winders. These tools can quickly and easily detune and tighten your bass strings when changing. This can be a surprisingly tedious process and uncomfortable for your hands, and these cheap tools can make the whole thing quite painless- particularly for upright bass.
D'Addario EJ16 Phosphor Bronze Light Acou Guitar Strings 3-Pack w Pro-Winder
D'Addario EJ16 Phosphor Bronze Light Acou Guitar Strings 3-Pack w Pro-Winder Price: $24.99
Peg Winder Bass Guitar Ergonomic Built In String Stretcher and Bridgepin Puller
Peg Winder Bass Guitar Ergonomic Built In String Stretcher and Bridgepin Puller Price: $11.92
Guitar Bass 3 In 1 Maintenance Tool, String Peg Winder, Strings Cut, Extractor
Guitar Bass 3 In 1 Maintenance Tool,  String Peg Winder,  Strings Cut,  Extractor Price: $9.27
Dr. DUCKS POLISHING CLOTH KIT w FREE POWER STRING WINDER for GUITAR BASS DRUMS
Dr. DUCKS POLISHING CLOTH KIT w  FREE POWER STRING WINDER for GUITAR BASS DRUMS Price: $8.00
Acoustic Electric Guitar Bass Peg String Winder Head Pin Puller Tool Black
Acoustic Electric Guitar Bass Peg String Winder Head Pin Puller Tool Black Price: $3.52