This keeps your collar looking good all day, especially when wearing dress shirts without a tie.  When wearing a tie I use them without the magnet, as the tie pretty much keeps your collar in place. The magnets are strong and cannot be felt while wearing them.

Two cons, 1)The high price 2) The magnets are not durable, and I have had two crack because I forget they are on when taking off a tie, and they fell and hit the bathroom tile floor. Luckily they sell replacement magnets. 2.5 inch work well for most collars, but if you wear an english spread (such as found  on Charles Tyrwhitt shirts) you will want to opt for the shorter 1.5 inch version