This is a simple, subminiature size, axial lead mounted rectifier diode. Often used for reverse voltage protection, the 1N4001 is a staple for many power, DC to DC step up, and breadboard projects. The 1N4001 is rated for up to 1A/50V.
We use these little buttons on everything! These Miniature Single Pole Single Throw switches have a good click to them and are breadboard friendly. Perfect as a tactile reset switch. These momentary buttons are rated up to 50mA.