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.
Multifunctional String Peg Winder for Guitars Bass Repair Luthier Tool K1Q3
Multifunctional String Peg Winder for Guitars Bass Repair Luthier Tool K1Q3 Price: $4.68
String Winder, Bass Guitar type
String Winder,  Bass Guitar type Price: $7.69
Guitar Bass Peg String Winder Head Tools Bridges Puller Drill Hexagonal 'Re DFI
Guitar Bass Peg String Winder Head Tools Bridges Puller Drill Hexagonal 'Re DFI Price: $5.00
Guitar Bass Peg String Winder Head Tool Bridges Puller Drill Hexagonal Remove KH
Guitar Bass Peg String Winder Head Tool Bridges Puller Drill Hexagonal Remove KH Price: $5.05
Guitar Bass Peg String Winder Head Tool Bridges Puller Drill Hexagonal Remove TS
Guitar Bass Peg String Winder Head Tool Bridges Puller Drill Hexagonal Remove TS Price: $4.00