Lead mounted standard recovery rectifiers are designed for use in power supplies and other applications having need of a device with the following features:

High Current to Small Size
High Surge Current Capability
Low Forward Voltage Drop
Void−Free Economical Plastic Package
Available in Volume Quantities
Plastic Meets UL 94 V−0 for Flammability
These are Pb−Free Devices
A diode is a device which allows current flow through only one direction. That is the current should always flow from the Anode to cathode. The cathode terminal can be identified by using a grey bar as shown in the picture above.

The 1N5408 Diode, the maximum current carrying capacity is 3A it withstand peaks up to 200A.
Common Applications of the 1N5408 Diode include:

Can be used to prevent reverse polarity problem
HV supplies
Half Wave and Full Wave rectifiers
Used as a protection device
Current flow regulators