Spin On is HF156, internal is HF155. I was told that HiFlo makes the KTM OEM filters... Not sure if that is the case but they seem to be much cheaper than the KTM branded ones
Spunkys has the K&N brand #155 and #156 at a few dollars more than the Hi-Flo filters but lots cheaper than OEM brand. The Hi-Flo, K&N and KTM brand filters are all manufactured in a factory in Thailand.........The same factory? Could be.