Horizontal Carousels are best for high density, high speed distribution in broken case picking and small parts.
Key specifications: Carrier width (for totes), shelf depth and weight capacity, carrier height, number of carriers, safeties, if any. Foot print of floor space available. Maybe double stacked for more density.
Key considerations: Restocking rates, overall through-put of picked items (if very frequent relative, storage location size may be adjusted or other solutions maybe better), total cubic requirement, number of SKUs and software requirements. Minimum of two units recommended.