Because it is so heavy (500 g - 18 oz) and has that rebound effect, it is easily manipulated in order to optimise the rope’s placement. The streamline profile combined with its compacity (core in one piece and outer shell tightly fixed together) help passing through crotches: it doesn’t flatten on the branches and can be moved effortlessly.
It is mostly used as a complement of the classic throwbag, for instance in order to weigh down a throwline and let it down faster, or use its natural rebound in order to work a way through crotches. This helps manipulating the throwline in order to optimise the rope position in the tree, for a safer or more efficient access or climbing.
The PULSAR can also be used to weight down your rope during SRT access: the mechanical devices are easier to push up when the rope is a little tauter.