I just bought the Crimson Trace Grips (LG-460) for my K9. It also fits the K40, second generation frames. They replace you current grips. Here are the specs:
Fits Models: Kahr Arms K9 / K40 fullsize pistols
Technical Specs
Activation Instinctive Activation; Front Pressure Switch
Material Comfortable Rubber Overmolded Switch, Hard Polymer Side Panels
User Adjustable Both Windage and Elevation
Holster Fit Ultra-compact 3.3mm diode in our slimmest housing to date
Warranty 3 Years Complete
Beam Intensity 5mw peak, 633nm, class IIIa laser. Maximum output that federal law and technology allow.
Dot Size Approximately 0.5" diameter at 50 feet.
Power Source Two #2032 lithium batteries (included); over four hours of on-time use and a five year shelf life
I cheapest price I found was on eBay. The price was $230 shipped with a coupon from the manufacturer for batteries for life (one set per year).
This link is from CT:
www.crimsontrace.com/Home/Products/KahrArms/LG460/tabid/306/Default.aspx