Ekrin's Newest and Most Powerful Percussion Massage Gun The Kestrel maintains many of the same great features that make our B37 and B37S models so popular, while adding some great new features, including a smooth scroll wheel allowing a seamless transition between speeds, USB-C PD charging for fast charging & compatibility, a textured silicone grip, and an increased amplitude to 13mm for those seeking a deeper massage. Classic black color comes in a hard case. New white Kestrel comes in a neoprene soft case with a separate bag for attachments.