Sale Add Wish List Quick view Choose Options CrossBlock CrossBlock II for Dogs and Puppies 11 to 20 Pounds - Green Label (3 Month) CrossBlock II is a topical flea treatment for dogs that kills adult fleas as well as their eggs and larvae. It contains imidacloprid and pyriproxyfen, and start killing fleas within 2 hours and... MSRP: Was: $22.99 Now: $16.99 Choose Options