There are three main types of heat presses: clamshell, swinger, and draw.
Clamshell presses have a hinge between the upper and lower platens and open similar to a clamshell. The heated upper platen then closes down on the lower platen to provide the necessary pressure. While easy to use, the clamshell press does require that layout work be done directly under the heat source and may not be as well suited as other models when printing onto thicker garments, such as hooded sweatshirts.
Swinger, or swing-away, presses swing the upper platen away from the lower. This allows the user free access to the lower platen without having to reach under the heated upper platen, making garment arrangement and layout easier. Because the upper platen swings away, this type of press takes up more space than a clamshell.
Draw presses have a lower platen that pulls out toward the user. Layout can be done without the user reaching under the upper platen, but more workspace is required. This type of heat press machine involves a moveable work surface, requiring greater care to be taken to avoid designs shifting out of place before application.
Perhaps the most indispensable feature any heat press machine should have is temperature consistency across the upper platen. Cold spots in the upper platen can lead to substandard or ruined garments, so even temperature is key in producing the quality products you (and your customers) want.
Other features to look for in a heat transfer press are interchangeable platens and digital temperature and pressure readouts. Digital gauges ensure that accurate pressure and temperature are used during application, while interchangeable platens make application to different items much easier and more consistent.
When looking for the best heat press to fit your needs it is also important to consider the reputation of the manufacturer, service options, and available warranties. Also consider the purpose for which the press was manufactured. Some heat presses are made for light or hobby use, while others are made to handle a heavier workload.