Over the last couple years, we’ve all had to get a lot more comfortable with the idea of exercising at home instead of in a gym. But home workouts can only get you so far without some specialized equipment, and for low-impact cardio, few options are better than an elliptical machine.

If you’ve ever thought about buying one, though, you know that the types and features available can get a little overwhelming—and at the kind of price point we’re talking about, you want to be sure you’re getting what you need. We’re here to help you break down all the things to consider when shopping for an elliptical.

There are a lot of advantages to using an elliptical, and even more advantages to owning one. When it’s already in your home, you can hop on whenever you have the time, making it much easier to fit a workout into your daily routine—especially if things like “putting on pants” or “being looked at by other humans” sound exhausting.

Ellipticals are straightforward and easy to use, but still give you an effective cardio workout. Getting your heart rate up isn’t just good for cardiac health; it also helps you burn fat to lose weight. And although ellipticals make most people think “cardio,” they also engage 80% of your body’s muscles, helping you build strength in your upper back and arms, as well as your quads, glutes, and hamstrings. They’re also a low-impact workout: because your feet don’t leave the pedals, there’s less strain on your joints and a lower risk of pain or injury.

Elliptical machines come in three main types: center drive, front drive, and rear drive. These names refer to the position of the elliptical’s flywheel, the weighted disc that provides resistance when you move your feet and helps to maintain the machine’s stability. Where the flywheel is positioned can change your experience on an elliptical, so it’s important to consider what kind of workout you’re looking for before you choose a machine.

Front Drive - A front drive elliptical has the flywheel positioned ahead of you, with your toes pointing at it. The pedals on front drive ellipticals are positioned at a bit of an angle, providing a workout that can feel more like climbing stairs. They also often require you to lean forward a little, engaging your back and other upper body muscles.

Rear Drive - Rear drive ellipticals, on the other hand, have more of a flat-ground feel to their movement, and are more likely to let you adjust the incline yourself. And because their pedals are lower to the ground, rear drive machines are the easiest to step into.

Center Drive - If you’re space-conscious, a center drive elliptical might be the choice for you. On these machines, the flywheel is positioned alongside your feet, minimizing the extra bulk. Center drive machines are well balanced and provide a workout that feels similar to a front drive: some elevation to your steps, a little like climbing stairs, but without the front-drive’s need to lean forward. The pedals are also typically closer together, putting your hips and knees in a more natural walking position.

The vast majority of ellipticals allow you to change how hard it is to push the pedals, called the resistance level. Some machines have just a few levels, and some have dozens.

Choosing the right resistance level can seem overwhelming at first, but don’t be tempted to overwork yourself, or you might end up with an injury. Start slow, and you’ll quickly see yourself bumping the resistance level up. The more resistance levels a machine offers, the easier it is to customize your workout: you can use different levels for different intensities or types of training. High resistance will help with a shorter, high-intensity workout, and lower resistance creates a more endurance-focused workout. And with more resistance levels, you can easily see the progress that you’re making as you bump up the difficulty.

Ellipticals used to be decidedly noisy. The design of older models caused loud whirring sounds whenever they really got going. Today, machines are quieter, but can still sometimes thump or hum, especially as they age and parts begin to wear or loosen. The increased use of magnets to provide resistance in ellipticals has cut down on both noise and general wear-and-tear, lengthening the machines’ useful life—but most are going to make some amount of noise. The quietest models are often the higher-cost ones, which use electromagnetic resistance for smooth performance.

Older models of elliptical machines used a strap or belt to connect the pedals with the flywheel. These machines, with all their moving parts and the opportunities for friction, could be extremely noisy. Most modern ellipticals, on the other hand, use magnets to create resistance.

Many ellipticals use a fork to hold magnets near the flywheel. Adjusting the distance between magnets and flywheel, either by hand or via a control panel, increases and decreases the resistance. Higher-cost models of elliptical machine use what’s called an eddy current brake system. This system uses electromagnets to change the resistance on the flywheel, avoiding friction for a smooth, quiet workout that offers more precise resistance control and reduces strain on the machine’s parts.

One particularly helpful optional feature on elliptical machines is a digital monitor. These built-in computers can calculate your workout time, “distance” traveled, heart rate, calories burned, and some can even interface with your wearable tech (like smartwatches) to collect precise data and integrate with any health-monitoring apps you use. Higher-end machines can use heart rate data to increase or decrease resistance automatically, keeping you in an ideal range for your workout.

Some ellipticals even come with digital subscription services that can include social functions like leaderboards or live classes, if you need the motivation of an instructor or some friendly competition. Needless to say, all these functions will add cost—both to the price of the machine itself, and also for any ongoing subscriptions. It’s important to consider up-front what kind of workout experience you want from your elliptical—but whatever you’re looking for, there’s a model out there that can meet your needs.