This is a Stihl 045 super powerhead. It is 87cc, 6.1 hp.
 
The crankcase bearings are new old stock OEM, it has a new aftermarket bar oil cap, wrist pin bearing and piston kit with new OEM rings. The cold compression is just under 150 psi and the rings are not yet seated.

This also has a dual port muffler (which technically makes it a super II), good Bosch electronic ignition, tool less clutch, lightly used 3/8 pitch 8 pin replaceable rim sprocket and lightly used aftermarket air filter. 

I have only used this enough to get it nice and warmed up to make sure the ignition would not fail at operating temperature.

I will consider a reasonable best offer. Feel free to ask questions.