Remote Reservoir shocks offer more consistent performance and ride quality over a variety of different climates and temperatures. The increased volume of oil helps the shock run much cooler than a standard shock and compensates for oil expansion due to heat.
There are basically two types of remote reservoir shocks. One being a fixed type, often referred to as a "piggyback" style remote shock where the reservoir is permanently mounted to the shock body. The other type leaves the reservoir loose, connected to the main shock body by a length of hose. This type gives options for mounting the reservoir and can make it possible to run a remote reservoir shock in a tight space.