G'day,
I have come across a couple like this only, the decompressor hole in the head is blanked off and the the head has a deeper dish (low compression head).
I had to helicoil a stripped plug in one of these because fitting a normal head was ripping the cord out of my hands.
I was told these were made for export overseas.
I actually like to feel the compression when I start this type.
Cheers
