Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Will this fit on a Nikon D7100?
Document: Easy to useworks as described.Good fit with my Nikon D800Highly recommend for family photos that include the photographer.
It fit on my Nikon 300S perfect, worked like a champ.Now I can entertain small kids and take their photo.
Infrared units need line of sight and this is far better.Nikon quit making its unit. Fine with me. The Nikon remote was hundreds of dollars and no better. I don't want their remote that is connected via a wire. I like being able to shoot from all sorts of locations around the camera, especially with wild life that would otherwise not come close were I standing there.Now that I've found the cause of the loose fit and put in my own batteries the remote is a gem. The receiver however, requires a jeweler's screw driver to get into it.
At half the price of Nikon's remote, I tried this product starting about 2 months ago with the new D800. As the cited "best" review with a low rating indicates, this product can be difficult to attach to the port. That's partly the fault of Nikon who put a silly rubber cover on the port that is held in place by an extended bit of rubber from the back. This causes the rubber bit to constantly get in the way when putting the sensor into the port on the D800. With a bit of care and time, it fit like a glove and came off with total ease.
Comes with Panasonic battery. Wish was smaller like the Nikon ML-L3.Has a slider cover that protects shutter button from accidentally pressing.Shutter button is a little loose, rattling sound when shaked. Wish was more solid and diddn't move around but I can live with it.Channel buttons are small but a channel pin comes with kit which is on the supplied wrist strap.Comes with small drawstring suede pouch with divider to separate receiver and transmitter or spare battery.Small 2"x2" user manual can fit in pouch.What I don't like is that on my camera it doesn't align directly straight up when connected.
Does everything it advertizes very well - fit/appearance quite good. On the down side it appears to be a bit delicate and when installed on the camera replacing a lens is a real trick
I was looking for a small easy to use, wireless shutter release, that did not sit on the camera hot shoe. This device fit the bill perfectly. And it was reasonably priced at under $100. I would highly recommend this product to other serious photographers.
No biggie I think, I go to use it this morning and no go. So I get out my pliers to take it off ( won't need pliers if you are a girl with small but very strong fingers or a guy normal size man hands are not going to fit)threads off just fine but noticed one of the male prongs is still in the camera port! Ruined! If you can handle putting it on and taking it off everytime go for it. Its a really cool design. Just not sturdy enough.
I bought this to use at a wedding I photographed. I had my D200 at the front of the ceremony on a tripod being run by this remote, while walking around capturing different angles handheld with my D7100. I pretty much just set the camera up and hoped for the best. EVERY picture was in focus thanks to the half press of the remote button for AF, before fully pressing it to take the photo. At times I was about 75' away without any line of site and it never missed a button press.
Works like advertised. I bought it for my wife but she has no complaints about it. Works with her Nikon D200.
Answer: You don't need this. The D7100 camera is compatible with the Nikon ML-L3 infrared shutter release. It is alot cheaper than this product and it is basically a remote. Check it out.http://www.pixiq.com/article/nikon-d7100-official-announcement