If out of stock allow a couple weeks for next batch to ship out.
 
The cylinder heads come with a dome of your choice only buy these if you want additional or replacement dome.
 
For Canadian orders shipping doesn’t include the current and constantly changing tariffs and duties. Returns will not be accepted for those who decide not to pay these fees.
 
Domes
Fitment is two year ranges 
05-21 and 20-22 X model are the same and the first option.
22-26 and 23-26 X model are the other option.
The engine changed in 22 on the motocross bike and they didn't change the off-road X model till the following year. The outside portion of the head is the same but the domes are slightly different in design.
Enduro - 91+ Octane This offroad dome makes the most torque with the smoothest delivery. The power is focused from off idle through the mid range.
MX - 91+ Octane This dome is for mx for medium and large tracks with power broad for mid and top with good over rev.
SX - 93+ Octane This dome is good for smaller or tighter tracks. More explosive hit in the mid range.
100 Octane - Broad mid and top power increase over the pump fuel dome. 
110 Octane -Sharpest mid range hit with focus on quicker response with a hard pull in the mid range to to top.
Blank - This dome has the treads and outside machined but the inside hasn't been so you can cut a dome to your own specs. This is great for other engine builders.