Just for fun, I measured several of the TI dice:

Little Professor 1978 1990C - 3.35mm x 4.44mm
TI-1270 0970 - 4.05mm x 4.80mm
Entex Baseball 1 1000 - 4.47mm x 4.63mm
Stop Thief 0980 - 4.57mm x 4.93mm
TI-30 0980 - 4.59mm x 4.93mm
Merlin 1100 - 4.75mm x 5.56mm
Total Control 4 1400 - 4.76mm x 5.79mm
Entex Baseball 3 1100 - 4.77mm x 5.73mm
Speak&Spell CD2302 - 4.88mm x 6.34mm
Speak&Spell 0281 - 5.36mm x 5.45mm
Speak&Spell 0271 - 5.44mm x 5.85mm