A rash of sexual assaults in Newburyport, Massachusetts has prompted local police to offer the nationally renowned Rape Aggression Defense (R.A.D.) system for women.

According to the Newburyport Daily News, the free R.A.D. course starts Nov. 20, and continues on Nov. 21, 24 and 25. Each class will take place from 6:00 p.m. to 9:00 p.m. at Bresnahan Elementary School. The instructors are nationally certified R.A.D. instructors and Newburyport police officers Dani Michalek and Megan Muldowney.

Police are still looking for the man they believe to be responsible for five sexual assaults over the last several months. He is described as a a thin, white male in his early to mid-20s wearing a hoodie. Victims haven’t been able to get a good look at him, because his usual M.O. is to catch his victims by surprise, grab them quickly and throw them to the ground, City Marshal Thomas Howard said.

As the Daily News reports, local officials are urging women to be aware of their surroundings and refrain from distracting activities like listening to music on earbuds and looking at smartphones while walking. Women should also walk in pairs, officials said.

The R.A.D. class is designed for women 15 years of age and older. If you’re under 18, you need a signed permission slip by a parent or guardian to attend. Enrollment is limited to 12 participants, but as police expect demand to be high for this class, they’ll likely offer more R.A.D. classes next year.