2PCS Mini Push Pull Linear Solenoid Electromagnet 5mm Stroke DC 5V~12V 25Ω Open Frame Mini Frames Actuator Electric DC Magnet Solenoid DS-0420S

Works well

Few things about this solenoid for potential buyers: First, I measure about 8-8.5 ohms DC resistance and the current draw is between 485 and 552 mA (0.485 - 0.552 A DC) with a 12V 1-ampere Triad wall-wart. Second, this is a pull solenoid only, so it's use is mainly for releasing a button or lever from a "pressed in" position (the return spring is responsible for "pushing" and it has no power). Third, the draw pin is not captive, it just sits in the body, so you need to "assemble" it in front of your whatever and make sure without power the button or lever the solenoid is in contact with is pushing it in, then when you power up the solenoid it will pull in the pin and release the button or lever. Hope that helps.

to me the springs are a little light for my needs but was able to change a spring and it works as it should for my project

Keep them in the 9V-12V range, and they work great!

Works great with 12 volts, 8 AA batteries

They work as advertised. Beware that there is nothing holding the rod in after you turn it off so it does go flying a bit. Also, I found that it may need an external 5V and a transistor to run off of an Arduino. Works perfectly for my project.