A Study to Assess the Usability of the Embrace Seizure Detection Watch in Children and Young Adults With Dravet Syndrome

This sub study will include up to 20 participants who meet the entry criteria for the main
Study ZX008-1503 and who are willing to wear the Embrace watch and use the Embrace Alert app
for 12 consecutive weeks. Those invited to participate will undergo all procedures included
in the main study during their participation in this sub-study,

Inclusion Criteria:

- Subject is willing to wear the Embrace watch on the wrist (alternatively ankle, if
needed for younger children). Subjects are asked to wear the watch for as many hours
of the day as possible and for the entire night, if possible, for the duration of the
sub-study.

- Subject's parent/caregiver is willing to use the Alert App.

- Subject/subject's caregiver is willing to ensure that the Embrace watch remains within
close proximity of the paired iPod Touch running the Empatica Alert app.

Exclusion Criteria:

- Subject has a known hypersensitivity to any of the Embrace device materials.

- Subject has a clinically significant condition, or has had clinically relevant
symptoms or a clinically significant illness in the 4 weeks prior to Visit 1, other
than epilepsy, that would negatively impact study participation, collection of study
data, or pose a risk to the subject.