This version of Testosterone
was first popularized under the name “Testolent” and was produced by
the Sicomed Pharmaceutical house. For awhile, is was a rare find on the
black market, but the recent availability of various powders and the
emergence of all the various underground labs, have made this version
of testosterone more readily available. It’s
simply Testosterone with the Phenylpropionate ester attached,
which we usually see more commonly attached to the Nandrolone
base compound, giving us Durabolin (often called NPP, which is short
for Nandrolone Phenylpropionate). I guess this would be called “TPP”
This particular ester gives us an active life of 4-5 days, falling just
between the Propionate (short) and Cypionate (long) versions of
Testosterone. I recently had the opportunity to try this compound, and
actually like it quite a bit- it’s perfect for someone like me who
likes short esters like propionate, but is too forgetful to inject
every other day! Clearly, you’d get best results
shooting this compound every third or fourth day, or roughly twice a
week. Other than the unique ester, there’s nothing much to
say about TPP that isn’t applicable to any other form of testosterone.
Personally, I’ve experienced less water retention with TPP when
compared with testosterone Cypionate, or Enanthate, and really no more
than I’ve experienced with Testosterone Propionate.
Testosterone exerts its effects by promoting increased nitrogen
retention in the muscle 
Testosterone also increases levels of the
growth factor IGF-1 in both the muscle tissue and the liver.
Testosterone, regardless of the ester, also has the ability to increase
the activity of satellite cells,
an active role in
repairing damaged muscle. Testosterone exerts these effects primarily
by genomic mechanisms, meaning that it binds to the androgen receptor
(AR) and initiates gene transcription to deliver its message.
Stimulation of the AR promotes various of the AR dependant mechanisms
for both muscle gain and fat loss 
as well as reducing catabolic
glucocorticoid hormones 
increasing red blood cell production 
Testosterone, once in the body, can be converted to both estrogen
(through a process known as aromatization) as well as
Dihydrotestosterone (through a process known as 5alpha-reduction).
Estrogen is typically the catalyst for many side effects such as
gynocomastia, water retention, etc...while DHT is often behind hair
loss and prostate enlargement.
Due to its recent reemergence on the black market, and high
availability, the cost of TPP is currently low, and I predict it will
become very popular in coming years.