It looks like you're referring to a laptop charger that outputs 18.5V at 3.5A, commonly used for HP laptops with a yellow tip connector. This type of charger is often compatible with older HP models and may fit several devices in the HP Pavilion, HP EliteBook, or HP ProBook series.

Here are some things to keep in mind when looking for a replacement or additional charger:

1. Voltage and Amperage: Ensure that the charger you buy provides 18.5V with 3.5A (or higher amperage) to ensure compatibility with your laptop. The voltage needs to match exactly, but a higher amperage rating is usually okay, as the laptop will only draw the current it needs.

2. Connector Type: The yellow tip is specific to certain HP models, so double-check that the charger has the correct connector size and polarity.

3. Model Compatibility: Always verify your exact laptop model to ensure the charger is compatible. Some HP laptops may use different voltage or connector specifications.