1.SIP N SEAL TO GO LID & SMALL CUP: The small cups with Sip N Seal lids are compatible with Nutri Ninja Auto-iQ BL480 BL481 BL482 BL490 BL640 BL680 BL450 BL482 BL682 BL642 BL640 and Duo Blenders. Please See 4th Picture for Model Number location. 2.To ensure these are the correct cups for your blender, please pay closer attention to the sizes on the images and description. These cups have 3 7/8' diameter. Measure your cup diameter and it must be about 3 7/8' which is a little less than 4'. Does NOT fit Ninja Blenders that have a 3 1/8' diameter or came with a 16 Ounce Cups. Please see all pictures for size reference and fit. Does NOT fit Ninja Blenders that have a 3 1/8' diameter or came with a 16 Ounce Cups. 3.TAKE THEM TO GO: Unlike other replacement cups, the 18oz cups include sip n seal lids so you can easily blend and run. You no longer have to drink your whole beverage in one go. Instead, screw on the handy To Go lids and take your drink with you! Need one for your BFF or partner? That's why we made a 2 pack! 4.HIGH QUALITY: Our spare replacements have standard and metric measurement markings scale line for easy measurement of your drink contents so you can make the perfect mix everytime. For added convenience, it is also top rack dishwasher and BPA Free.