Keyword Analysis & Research: why is it called a tri wall

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
why is it called a tri wall	0.62	0.8	273	93	27
why	0.59	0.1	9555	54	3
is	0.73	1	451	15	2
it	0.44	0.7	7841	16	2
called	0.28	0.3	7345	24	6
a	1.93	0.4	1696	79	1
tri	1.55	0.7	8083	68	3
wall	0.4	0.4	3183	46	4

Keyword	CPC	PCC	Volume	Score
why is it called a tri wall	0.2	0.3	7273	100