Advocate PetTest 21G Twisttop Lancets - 50 per Box Advocate offers a complete range of quality lancets to ensure that accurate blood samples can be obtained with any type of coat, quickly, easily and consistently. PetTest 21G Twisttop Lancets are designed and manufactured with the greatest degree of precision and for better sampling on dogs and cats. The tri-beveled needle tip enhances pet comfort and reduces tissue damage. For single use only.