Specs from the sites: (I haven't verified the weights, but PE does appear to be significantly heavier unless that's a shipping weight):
Starcase:
2U - 7 lbs
Interior: 16.1 x 14.25 x 2.75
4U- 9 lbs
Interior: 16.1 x 14.25 x 6.25
Penn Elcom
2U- 9lbs
Interior: 14.02 x 16.02 x 2.91
4U- 11.2lbs
Interior: 14.02 x 16.02 x 6.42