Help needed! How do I read my needle measure!

Portia 💛 • 7 years ttc #1, 1st FET 30/01/19 = BFN 2nd FET 24/03/19 - BFN 3rd FET 08/07/19 = BFN 4th FET 14/11/19 = BFN 5th FET 22/03/20 = BFN

I have to start my buserelin injections tomorrow and I’ve just realised I can’t understand my needle measures 🙈 I have to take 0.5ml each day, but my needles are in units! It goes up to 50units. Please some one help me and tell me what the correct number of units I need to fill the needle up to in order to get 0.5ml. Xxx