The FK100 is perfect for Smart Start SBI (SBI212 and SBI224) auxiliary and start battery connections.  One of the most common failures the REDARC technical support team hear about with dual battery installations is a failure of the fuse/holder. This failure can result in the fuse and holder melting causing the connection to be lost and, therefore, no charging of your auxiliary battery. This situation is usually diagnosed as a blown fuse however it is more likely attributed to a poor quality fuse holder. Poor quality fuse holders often don’t make adequate contact with the fuse which can allow dirt and dust to get in between the contact points. This causes excess heat to be generated due to the high resistance. This excess heat can be enough to melt the fuse and the holder. Even if the fuse holder doesn’t melt, you could be losing valuable charge to heat dissipation.
The REDARC 60A Fuse Kit is equipped with high-quality fuses and a fuse holder to fit the cable required for the specified current and make a solid connection. Each REDARC fuse kit features adhesive-lined heat shrink to ensure reliability through any terrain.
 
Kit Includes:
2x Fuse Holders with Fasteners
4x 100A Fuses
4x Cable Lugs 25-8
4x Cable Lugs 50-8
4x Adhesive-lined heat shrink 

Damage and wear to packaging; Recommended Retail is $160, so at $80 this is a steal.