That's a Vox CoAxe pickup. It's mounted and adjusted by 2 screws between the 2+3 and 4+5 pole pieces, just like a P90. It's hard to see in your picture because the screws are black.
It doesn't really sound like a P90 as it leans a little more towards a Fender single coil. It has the output of a P90, but hum cancelling.