Its gets super confusing when a customer looks at a lash thats dramatic short but fluffy. 
MM means millimeter, the length of the eyelash. These two different style lashes (dramatic lash and a natural lash) that are 25mm lashes. 
25mm mink lashes (1).png
Use this as a guide to find the right length:
 
Strip eyelash lengths
Size Chart for Lash lengths for strip lashes.
  • 6-8mm ( thinner lashes for natural eyelash)
  • 10mm ( training lashes)
  • 12mm ( Average natural lashes length )
  • 14mm ( Short Lashes)
  • 16mm ( most popular sizes)
  • 18mm ( Medium volume lashes )
  • 20mm ( Medium Long)
  • 22mm ( Long and bold )
  • 25mm ( Dramatic and bold while still looking natural) also one inch long.
  • 30mm and up ( Drag Queen Length)