SSF or SRF 550 Natrelle Inspira implants?

There are many implant variations. The Inspira line uses a 3 letter system to delineate any particular device. The first "S" refers to the "smooth" outer surface of the device. This differs from textured and is fairly standard in the realm of round devices (texture is more common in shaped devices as it serves to hold the implant in place). The second letter refers to the gel variety. Allergan offers three devices which grow increasingly firm, as one moves up the scale secondary to gel cross linking. The "R" stands for "responsive" and is the softest and least cross linked. The "S" refers to "soft touch" which is slightly more firm and more resistant to rippling. The "C" is the "cohesive" or form stable/gummy bear variant which is the firmest and is the same gel available in the shaped devices. The final letter is the the profile. The "F" in your particular case refers to the full/high profile device which confers greater projection and volume for a given device width. In my practice, the vast majority of patients have smooth round, responsive devices in any given profile. "Soft touch" is typically reserved for those in whom rippling is a concern (thinner patients with little native breast tissue for camouflage).As always, discuss your concerns with a board certified plastic surgeon (ABPS).

There are three classes of inspira implants based on the degree of firmness and cohesiveness of the implant. The firmest and most cohesive implants are the SCF implants. These are the most form stable, and resist rippling. This is followed by SSF implants that are softer, and less form stable. The last implant, which is recommended for you is the SRF, is the softest, least cohesive implant. The pricing on these implants are contingent on the degree of cohesiveness: the more cohesive, the higher the cost. The advantage of a high degree of cohesiveness is resistance to rippling, which in individuals with very thin breast tissue may be important. You appear to have good tissue, and likely would do well with the softer implants. The decision tree then breaks down into price. Both the SSF and SRF will give you a great result. I can't think of a reason to spend more money on the firmer implant. Good luck!Matthew C Camp M.D. 

Thanks for posting, this is an excellent question.
The most important choices are the diminesions of the implant, the choice of fill (silicone versus saline), the inscision site, the position (over or under the muscle), and the inclusion of fat grafting.
Your photos show an aesthetic chest that is symmetrical, proportionate and aesthetic. With the implant size you have chosen you may notice a slightly fuller and larger upper pole than what is naturel. Most breast augmentation patients want these changes.
You are thin so there will likely be some implant show along the side(s) and bottom. Ways to reduce rippling and show include fat grafting, positioning the implant below the muscle and using a more chesive gel. Although there is a difference between the two implants I am not certain this will be evident once they are placed.
I would suggest consideration of two things. Firstly, if having a fuller upper pole is important use the more cohesive implant. Second, place the inplants on your chest in a sports bras. Hold them and decide which one ‘feels’ better. This is a personal decision that differs between patients.
At the end of the day I think you will be equally satisfied by either of the two implants.
Best wishes on your journey,
Alexander Anzarut