FLOCK 4S-28 is a CubeSat (3U) satellite, also known as Flock 4s-28, manufactured by PLAN and launched on January 24, 2021, from LC40 at AFETR using a Falcon 9 launch vehicle. The satellite's dimensions are 0.3 meters in length and diameter with a span of 0.3 meters, and it has a dry mass and launch mass both equal to 5.7 kilograms. It is equipped with solar cells for power generation along with batteries, and its payload includes PS0, PS1 or PS2 imaging equipment under the Dove 2460 series. The satellite's configuration consists of a box shape with two panels. Its mission is focused on technology purposes and it has an expected lifetime of about one year in ISS orbit and two to three years in SSO.