Features: These modules work with all standard SD cards. Dependent on your library 1 to 2 GB recommended for embedded use much more is just crazy overkill for most applications. Easy to wire to any microcontroller that has serial peripheral interface support (or any microcontroller with a programmer willing to write serial peripheral interface protocol from scratch. Easy to use examples, and instant compatibility with the built in library. Working voltage 3.3 & 5V(DC both required), 7 wires required (including power and ground). Specifications: Working Voltage: 3.3 & 5V Compatibility: for SD card Size: 5.1*3cm/2*1.2in Quantity: 5pcs Weight: 7g(approx.) Package Includes: 5 x Modules 1、These modules work with all standard SD cards. 2、Dependent on your library 1 to 2 GB recommended for embedded use much more is just crazy overkill for most applications. 3、Easy to wire to any microcontroller that has serial peripheral interface support (or any microcontroller with a programmer willing to write serial peripheral interface protocol from scratch. 4、Easy to use examples, and instant compatibility with the built in library. 5、Working voltage 3.3 & 5V(DC both required), 7 wires required (including power and ground).