Top Bank Trig is on a smaller hill 288 meters (946ft) of height in the Plynlimon range of hills.
To reach the cache is a fairly demanding walk and a gentle introduction to the higher and more demanding Moel Y Garn but rewarded with stunning views over the Dyfi estuary.
Plynlimon (anglicised from Pumlumon in Welsh, meaning "five peaks") is the highest point of the Cambrian Mountains in Wales, and the highest point in Mid Wales. It is a massif that dominates the countryside of northern Ceredigion.
The highest point of the massif itself is Pen Pumlumon Fawr to the south east at 752 metres (2,467 ft).
Its other important peaks are Pen Pumlumon Arwystli, Foel Goch, Y Garn, Pen Pumlumon Llygad-bychan and Pumlumon Fach.