Simmons, Sealy and Serta are the largest manufacturers of innerspring mattresses in the United States. These manufacturers along with Tempurpedic control over three quarters of all mattress sales in the US. For the sake of simplifying this subject, we will confine our comparisons to innerspring mattresses only. The flagship brands of these manufacturers are as follows: Simmons Beautyrest, Sealy Posturepedic and Serta Perfect Sleeper.
Simmons Beautyrest utilizes encased pocket coils in various coil counts, heights of coils and wire thicknesses (wire gauge). Simmons has made pocket coils famous in their Beautyrest line. Pocket coils are known for better surface conformability and less motion transfer. Pocket coils are heat welded at the center of the coils, not at the top like more conventional bonnel, LFK or continuous coil designs. When coils are attached at the top of the coil, individual coils are less independent which is part of the reason for less motion transfer in pocketed coil designs. Most Simmons Beautyrest mattresses are foamed encased and single sided. Simmons pioneered single sided mattresses a few years ago. In my opinion foam encasing pocket coils is the best way to stabilize the units. When Simmons made one sided beds (and I do understand the double sided argument), warranty and return issues dropped significantly. This is due to fact the pocket coil units were better secured and could not hammock as much and side to side movement of the units themselves was less likely.
Sealy Posturepedic uses a totally different type of innerspring. It is commonly known as an LFK type. This unit is generally 5 turns of wire and the coil shape itself is more hour glass shape top to the bottom, whereas pocket coils are more barrel shaped. The LFK unit Sealy uses has three straight sides on the surface and is sometimes referred to as a triple offset design. The top of the coil itself is not knotted like many bonnell coils, this allows more conformability on the surface of the unit itself. The coils on the surface on attached together by a small helical wire on the surface. Some argue that this also allows more movement on the surface of the coil, leading to greater motion transfer. This unit is very durable and reliable, but does offer a different feel than either Simmons Beautyrest or Serta Perfect Sleeper as I will explain next. Sealy encases the unit with a styrene type foam edge, which I do not like as much as the Simmons or Serta urethane foam encased edge.
Serta Perfect Sleeper uses a continuous coil design. The coils in this innerspring one continuous wire that runs from head to toe in Serta’s innerspring design. The helical wire that is used to attach the rows of continuous coils runs head to toe as opposed side to side as in the LFK unit. This supposedly limits side to side motion transfer. The coils themselves have no more than 4 turns (some say 3 turns). Sealy’s LFK and Simmons pockets have 5 turns of wire. The coils in Serta’s continuous innerspring unit are shaped more like spirals than traditional hour glass shaped coils found in LFK and Bonnell designs. These units are very stiff and are less conforming on the surface of the unit than either Simmons’ pockets or Sealy’s LFK.
In conclusion all these products are very reliable and durable, however there are differences in feels. I would say that both Sealy and Serta rely more on variance in feels and comfort with the various types of foams they use on the surface and in the interior of their products. Simmons gets more of the feel and comfort of their mattresses from the pocket coil itself. All three offer a wide range of products from extremely hard to very plush. My personal favorites would be in this order: 1. Simmons Beautyrest 2. Sealy Posturepedic 3. Serta Perfect Sleeper.