M1 are with adjust bar (at the bottom of the weights), F1 are without. Feedback is very important to us. It is impossible to address issues if we do not know about them!Faction is our ultimate goal. We work hard to earn your trust and future business. A If you receive a defective item, you may return it or ask for a discount. Due to time zones, our reply to your questions may not be immediately. If it's non-workdays, please kindly be patient and wait till Monday. The item "F1 Grade 1mg-200g Stainless Steel Scale Calibration Weight Set Certificate TOP" is in sale since Tuesday, August 6, 2019. This item is in the category "Business & Industrial\Healthcare, Lab & Dental\Medical/Lab Equipment Attachments & Accessories\Calibration Weights". The seller is "bestcollection999" and is located in Rowland Heights, California. This item can be shipped to United States.