Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: What is the difference between these and the Sennheiser PX 100-II for $45 on Amazon?
Document: I ordered the Sennhesier PX 100-II with iPhone controls from Amazon on Saturday and they arrived on Wednesday. Free Shipping. The product is awesome! Incredible bass and nice crisp tenor. I'm not an audiophile, but it sounds great to me. The iPhone controls work as they should on my 3GS; I should be getting a 4S soon, so I'll update once I've tried that.
Great quality and sound! Got what I paid for! Sennheiser PX 100-II delivers smoothly. Very happy with my purchase. Great buy.
This is the first review I have ever written and let me start off by saying I am not an audiophile or even close, I have a large music collection and I know what I like and these Sennheiser PX 100-II i are AMAZING with rich full sound.
Sennheiser PX 100-II i Light Weight Supra-Aural Headset with 3 Button Control for i-Pod,i-Phone and i-Pad (Black)This product was recommended by my friend. She called me the other day and usually I can hear static through the phone transmission. This time, while she was wearing her PX100, their was no static. It was as clear as a bell. I believe this is going to be a great buy and she doesn't recommend anything that she doesn't like.
The Sennheiser PX 100-II allow me to take calls and the sound quality is amazing on both ends! Not only can I hear the person calling perfectly, they can hear me just as well as if I'm speaking directly into the phone! I do wish the 3 button control on the headphone cord was located just a little bit lower on the cord, but it's a minor inconvenience.4) The headphones are extremely comfortable to wear for extended periods of time.
I own about 12 different pairs of in ear noise canceling phones, including top performing ones from Sure and Westone, etc and personally still like in ear a great deal for shorter periods and or when I want to block out commuting noise, etc.However, I have always been a fan of Sennheiser and remember the first pair I owned over 30 years ago. I have had the PX 100-II for just a few days but feel they are an outstanding value for sound and ultimate comfort.
Disappointing. Sennheiser PX 100-II headphones lasted 6 months of daily iPod use then went dead. I suspect the Sennheiser male audio connector. Other headphones work on the same iPod. The Sennheiser PX 100-II headphones will not work on any audio device.On the positive side, highly portable, good sound quality in a small package.Quality in electronics manufacturing is a lost value proposition. Hard to believe a quality company such as Sennheiser would design a great sound product but fail in the manufacture process.
I have recently purchased a pair of the PX 100 II-i's and am so glad I did. I had a pair of the original PX100's and they were awesome. They eventually broke after daily use for a year. So, when they broke I decided to go for the new ones. The sound is fantastic. I listen to all types of music and unless you want mind numbing bass, these guys should do just fine.
Only lasted 18 months. Then the right side is totally dead. North worth $60.I picked it because my 1st Sennheiser PX 100 lasted 6 years.
Eventually I contacted Amazon Support and they were outstanding! They assured me they would make it right and they contacted the vendor and the problem was immediately solved. The Amazon guarantee is excellent even when buying through an approved associated vendor. However, I would never ever purchase anything again except directly from Amazon. The outstanding Amazon service is easily worth the few dollars(in some cases) difference.
Answer: If you're asking about the price difference between the two PX 100-II models, the "i" ($72ish) has a three-button control for volume/pause/etc. and a mic for use with a phone. Besides that, I understand that they are the same headphones, drives, construction, etc.