Almost certainly no ester, because an ester isn't useful in a transdermal application, althought that doesn't explain their dosing schedule, which doesn't seem consistant with the prescription transdermal products out there.
"The esterification of the testosterone molecule at the 17-ß-hydroxy position makes the molecule hydrophobic and extends its duration of action. Deesterification of testosterone is not a limiting factor in determining its duration of action; the plasma half-lives and clearance rates for testosterone and testosterone enanthate are similar. It is the slow release of the hydrophobic testosterone ester from its oily depot in the muscle that accounts for its extended duration. The longer the side chain, the greater the hydrophobicity of the ester and the greater the duration of action. Thus testosterone enanthate and cypionate with longer side chains have longer duration of action than testosterone propionate."
http://jcem.endojournals.org/cgi/content/full/82/1/3