http://thmiii.com/?p=31 http://midequalitygroup.co.uk/sites/default/files/files/2014 MPEG Minutes May.pdf 
MSC-298 Metal Frame / Paper Cone
- Dia: 40 mm, height: 6.9 mm
- Output: nom .3 watt and max .5 watt
- Frequency range: 430-6000 Hz
- Net weight: 9 g
Taft MSC-298-1 Metal Frame / Paper Cone
- Dia: 45 mm, height: 8.8 mm
- Output: nom .3 watt and max .5 watt
- Frequency range: 600-6000 Hz
- Net weight: 13.4 g