Littmann Stethoscopes are available is a significant range of models and styles.
Here with some quick pointers -
Lightweight Series - Used for basic assessments, Blood Pressure (Because of the material performance expect a lighter sounds)
Classic Stethoscopes - Considered by many as the industry standard. The Littmann classics are can be used in general assessments.
Cardiology Stethoscopes - Designed for optimal acoustic performance, these stethoscopes provide the greatest range of sounds and enhanced clarity over other models.
Master Stethoscopes - These are the best acoustic performers in their respective categories. The single head helps to limit the ambient sounds.