I live in Southern California and this is a great collar for fleas. After cycling through Advantage II, Frontline Top Spot, Comfortis and Activyl this collar worked rather well. It took about a week for the collar to become effective. I also did not cut off any of the excess to maximize strength of product and used a small rounded zip tie to secure. Not sure if this would help but my cat needed all the help he could get. The reflectors are a nice addition and can be moved if you are careful releasing the delicate plastic clasp. They are pricey and considered buying from another vendor at a lower price point, however this product is counterfeited and wanted to make sure it was a real product, so I bought from Countryside Pet Supply.