Helibars is on the left. Convertibars is on the right.
The Helibars are taller than stock and I have had them since 1999 until now (June 2011). While they are more comfortable than stock, but on long distance ride, I always wished that they could be a little bit taller.
The Convertibars are about 2 inches taller and they are so well made. The adjustability is so much more flexible: the bars can be lowered or raised, the angles can be adjusted from 0 degree to +4, +8, -4, -8. The bars can also be moved fore and aft. The bars itself can be rotated 360 degree around its own axis.