A blade outer air seal assembly includes a support structure. A blade outer air seal has a plurality of seal segments that extend circumferentially about an axis and mounted in the support structure via a carrier. The carrier has a plurality of carrier segments that extend circumferentially about the axis. At least one of the seal segments have a base portion that extends between a first circumferential side and a second circumferential side and from a first axial side to a second axial side. A first wall axially spaced from a second wall. The first and second walls extend from the base portion to a first outer portion to form a first passage. The first wall has at least one slot engaged with a first carrier hook on one of the plurality of carrier segments. At least one of the carrier segments have a carrier window engaged with a support structure hook on the support structure.