I think you can get them at any major store (Target, Walmart, etc) or any pharmacy (Walgreens, Eckerd, etc.). I bought mine at Target...it was the only basal body therm they had. It works good, is digital...but it does beep when it is done. Some women say dh complains when it beeps, but I tend to wake up and temp as Dh is getting out of bed to get ready for work, so it has not been a problem for me. Good luck!