If I were to purchase:

Syringe with needle: TERUMO 3cc/mL Syringe 23G x 1.5" 25/Pack

I just want to make sure that the needles provided here are interchangeable, so basically if I were to purchase these on top:

Needles: TERUMO 18G x 1.5" 25/Pack

I could use the 18g to draw and the 23g to pin. The syringe w/ needle isn't a fixed structure correct?