The p49 glider shuttle is a period-49 oscillator discovered in its original form by Noam Elkies on August 1, 1999, and was the first period 49 oscillator to be found. It consists of four 90-degree glider reflectors shuttling four gliders around a period 49 track. The glider reflectors are based on pipsquirter 2 but use a slightly smaller version of the oscillator found by Karel Suhajda on January 24, 2003. Shuttling gliders in this manner is the only known way to construct period 49 oscillators, apart from stable adjustable glider loops. In terms of its 400 cells, it had been the smallest known period 49 oscillator before discovery of the Snark in 2013 made a smaller glider loop possible. Even so, the p49 bumper loop with 206 cells is the smallest p49 oscillator.
The original form of the p49 glider shuttleRLE: here