P44 pi-heptomino hassler is a period-44 oscillator discovered by David Buckingham on April 2, 1992. It was improved to the form shown here by Noam Elkies in April 1996. The oscillator consists of two pi-heptominos being hassled by two heavyweight emulators and four blocks.
Buckingham used two copies of this oscillator to make the first period 44 glider gun. This became obsolete in October 1996 when Buckingham found a gun that only used one copy of the oscillator.
In 1994 Dean Hickerson found a way to double the oscillator's period by adding two molds, creating the first period 88 oscillator. David Buckingham also found a way to triple the period before August 1994.
The first period 88 oscillatorRLE: here
The first period 132 oscillatorRLE: here