DAC conjugated CJC 1295 (Receptor Grade) is an hGH secretogue that is unique by way of an additional lysine molecule that is added to facilitate the DAC complex. This conjugation makes for a much longer half-life. DAC CJC 1295 tends to have a very limited availability everywhere due to expense and difficulty to manufacture. CJC 1295 DAC is a exceptionally designed peptide and is known for being the finest of the hGH secretogues. Receptor grade: 98%+ pure 2000mcg / 2ml glass vial. THIS PRODUCT IS INTENDED FOR RESEARCH PURPOSES ONLY. CAN BE HARMFUL IF USED INAPPROPRIATELY.
In the healthy human body, large amounts of growth hormone are stored in the pituitary. The cells within the pituitary release growth hormone in response to signalling by GHRH (Growth Hormone Releasing Hormone), Ghrelin (of which GHRPs - Growth Hormone Releasing Peptides - are mimetics), and are inhibited from releasing these stores by Somatostatin. GHRH and Ghrelin act on different populations of somatotropes (GH releasing cells). GHRP/Ghrelin increases the number of somatotropes releasing GH but not the amount released by each cell;
GHRH affects both the number of secreting cells and - moreso - the amount they each secrete.  GHRH and Ghrelin are released in specific patterns that vary depending on event and environment: post-exercise, in response to slow wave sleep, in certain stages of life and physical development, and so on.
Most people (even the diseased) continue to possess the ability to make GH in the pituitary. The problem is in the signalling of the pituitary to release it (and make more). So yes CJC is meant to replace the external administration of GH in some (but not all) cases.Even most people with diseases that affect growth hormone secretion retain the ability to continue to make GH in their pituitaries. The disease states and symptoms result, most typically, in altered (dysfunctional) GH release signalling and this also affects the ability of the pituitary to continue to make more GH. 
GHRH, which has a forty-four amino acid long chain (and a specific shape - thus making it a peptide as well as a hormone), has been marketed for the longest as Sermorelin. However, Sermorelin has been demonstrated to be degraded rapidly in the body and is cost-inefficient. But because most patients in need of GH therapy doretain the ability to produce and secrete their own GH, treatment with a GHRH-type analog remained hypothetically preferable to exogenous GH treatment. GH itself when administered exogenously results not only in "unnatural" release patterns, it results universally in downregulation of endogenous GH production - as do many hormones when applied exogenously. 
Sermorelin's limitations naturally resulted in a variety of formulations of GHRH analogs for therapeutic. The most effective (in terms of minimal degradation in the body - which is different from half-life) analogs with the longest half-lives were those created with an attached 3-maleimidopropionic acid (MPA) unit, which results in binding to albumin after exogenous injection into blood plasma.
The research chemicals CJC-1293 and CJC-1295 are GHRH (the 44-amino acid long version) with 15 aminos removed, thus a total of 29 amino acids, and bound to MPA.  MPA is also called Drug Affinity Complex, and CJC-1295 is often referred to as GHRH with Drug Affinity Complex (DAC).
Based on measured GH release in rats over a two hour period, CJC-1295 released twice as much GH as CJC-1293, thus rendering it preferable based on immediate effectiveness; however, CJC-1293 has a 9% edge in stability (meaning less degradation) with in vitro stability tests.
CJC-1293, over a two-hour period, results in a rise-fall-rise-fall type pattern whereas CJC-1295 results in more of an inverted-U shape with a more gentle and longer peak. 
In a CJC-1295 pulsatility study performed on normal non-GH deficient people reported plasma levels were between 1 and 2 ng/ml or 1000-2000ng/L one week after injection of between 60 or 90 mcg/kg of CJC-1295. In a 100kg man that is a 6mg or 9mg per week dose.
"Knockout rats" are mice with genetically removed M3 muscarinic acetylcholine receptors. The scientists conducting the study  inhibited these genes and the mice became dwarves.. Those mice, labeled Br-M3-KO mice experienced short stature and a shrunken pituitary. Scientists treated Br-M3-KO mice and normal control mice with CJC-1295 for eight weeks, resulting in complete growth restoration in the knockout mice as well as - notably - a restored pituitary size. More specific data regarding CJC-1295 can be extrapolated by examining some of the control mice, which were not "knockout rats" but still received CJC-1295. The controls, male and female, experienced both accelerated & increased overall growth over the non-CJC-1295-dosed controls. Referring back to the notable finding that pituitary size was restored in knockout specimens dosed with CJC-1295, it is equally notable that the controls who did receive CJC-1295 did not have any pituitary hyperplasia or growth of the pituitary whatsoever. This supports the conclusion that CJC-1295 is a substantially less risky treatment for non-diseased subjects, and a substantially more beneficial therapy for subjects with pituitary disease, than conventional (synthetic) GH treatment. 
In conclusion, CJC-1295 is an exciting treatment from the standpoint of cost efficiency, safety, and ease of administration when compared with regular GHRH or synthetic Growth Hormone treatment. It has been demonstrated to be as effective as GH for most uses, and vastly preferable for safety reasons where feasible. GH will not be fully supplanted by GHRH analogs such as CJC-1295 for reasons alluded to above, but the vast majority of treatments in the types of applications mentioned in this article will probably begin to use CJC-1295 for safety, cost-efficiency, and the need to administer only one or two times per week instead of multiple times per day. 
 Lewis UJ. Growth hormone: what is it and what does it do? Trends Endocrinol Metab 1992;3:117-121
 Synthesis and Biological Evaluation of Superactive Agonists of Growth Hormone-Releasing Hormone, J Izdebski, J Pinski, JE Horvath, G Halmos, K Groot and AV Schally, Proceedings of the National Academy of Sciences, Vol 92, 4872-4876
 Pulsatile Secretion of Growth Hormone (GH) Persists during Continuous Stimulation by CJC-1295, a Long- Acting GH-Releasing Hormone Analog, Madalina Ionescu and Lawrence A. Frohman, The Journal of Clinical Endocrinology & Metabolism 2006 91(12):4792-4797
 Neuronal M3 muscarinic acetylcholine receptors are essential for somatotroph proliferation and normal somatic growth, Dinesh Gautam, PNAS April 14, 2009 vol. 106 no. 15
*The latter article is intended for educational / informational purposes only. THIS PRODUCT IS INTENDED AS A RESEARCH CHEMICAL ONLY. This designation allows the use of research chemicals strictly for in vitro testing and laboratory experimentation only. Bodily introduction of any kind into humans or animals is strictly forbidden by law.