Single switches have short thin leads that don't stay on the breadboard. All other sizes have longer, stiffer wires and work well. I've attached a photo of a single switch next to a double switch. The little box they come in is disorganized. It comes with 9 compartments, but some compartments do not fit all circuit breakers of the same size, so the breakers are either placed in other compartments or in the 9th compartment, which contains one of three different sizes.
TWTADE/AC 24V 10A Coil Electromagnetic Power Relay 8 Pins 2DPT 2NO+2NC With Indicator Light And Socket Base -YJ2N-LY
9 Review
π NuTone 5901A000 Blower Wheel Assembly: Superior Efficiency and Performance
9 Review
Universal Rotary Cam Selector Latching Switches - VictorsHome Changeover Switch LW28-32 With 3 Positions, 12 Terminals For 690V, 32A Capacity
9 Review
Adjustable AC Current Sensing Switch: SZC23 No AL-CH Model, 0.2A-30A Range
14 Review