Directly from the EPA Web Site:EPA Acceptable use and regulations for refrigerant R1234yf; Small cans of refrigerant for MVA's, (R1234yf) containing 32 oz. or less, " DO NOT " require any certification.
National R1234yf Refrigerant Automotive A/C Recharge 8oz Self Sealing Can 2 Pack
R1234yf Refrigerant Automotive Air Conditioning 2 Can Recharge Kit
R1234yf Refrigerant Automotive A/C, 8 oz. Recharge Kit & Taper
National R1234yf Refrigerant Automotive A/C Recharge 8oz Self Sealing Can 3 Pack
National R1234yf Refrigerant Automotive A/C Recharge 8oz Self Sealing Can 4 Pack
R1234YF Refrigerant Can Tap Valve Set Professional For Automotive AC Repair