Yeah, ok, well this snake oil "sentiment" measures .64λ not .625λ, and that's a 6.5" difference, enough to retune a Scottish CB 5/8λ from the center of the CB band to the center of the 10m Amateur band.
The Hy-gain Penetrator is 6.5" longer than the Sigma 5/8, the I-10K, the Wilson Alpha...