My main pedals are dual Iron Cobra 900s, and as a backup I have dual Iron Cobra Juniors.
The Iron Cobras came with CB90F beaters, and the Juniors came with DS30 (dual-sided felt/rubber) beaters. I bought two CB90F beaters to replace the DS30s on the Juniors.
This is a very straightforward swap requiring only a drum key - there is a single bolt holding each beater in place, and the shafts are identical in diameter.
These beaters are lighter in weight than the DS30s. I consider this preferable - the DS30s had a tendency to rebound too far and bruise the top of my right ankle when playing fast. This has never happened to me with the CB90F beaters on either of my two sets of pedals.
There is an adjustable weight collar on the shaft which can be used for fine-tuning the weight distribution of the beater without adjusting the height at which it strikes the drum (if, for example, your batter head has a protective patch). Again, this is simple to adjust with just a drum key.
The beater shaft has a cylindrical T-bar at the top, and the beater head assembles around this. This allows the beater to 'self-level' its face against the batter head without permitting any side-to-side play - useful if moving the pedal between bass drums whose hoops are of different depths.
The beater heads are removable (again with a single drum key bolt) so they can be swapped very quickly. This means it's easy to use different beater faces (eg wood and rubber), and it also means that worn-out beater heads can be bought and replaced separately, without having to buy new shafts.
The only slightly tricky thing about fitting them is realising that they go on upside down and backwards, then rotate into position.
Overall, I would recommend these beaters as one of the easiest, yet most rewarding, upgrades to the standard beaters that come with lower-end pedals.
