What is about the size of your iPhone and cheaper than your morning latte, and can sculpt sexy stems and a firmer butt?

The answer: a mini resistance band.

If you've never used one, you're not alone. Resistance bands have gained props for being portable, affordable, and superefficient, but their mini-me version has received less attention. Utilizing this tool, however, can increase the impact of traditional lower-body strength moves, says Jim Smith, performance specialist and owner of Diesel Strength & Conditioning. It can also keep you off the sidelines: A new study found that using the band during squats helps remind you to push your knees out, which can prevent injuries such as strains and tears to your knee's ligaments (like your ACL).

Complete this resistance band workout from Smith as two supersets: Perform all the reps of the first move, immediately continuing to the second. Rest for up to 60 seconds and repeat for a total of four sets. Perform the third and fourth exercises and repeat this pattern, completing a total of three sets.

1. Glute Bridge

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Loop a mini band above your knees and lie faceup on the floor, knees bent and the soles of your feet turned toward each other (a). Raise your hips so your body forms a straight line from knees to shoulders, then drive your knees outward (b). Pause for up to three seconds, then return to start. That's one rep. Do eight to 12.


2. Lateral Shuffle

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Stand with your feet slightly wider than shoulder width, knees bent and a mini band looped around your ankles (a). Step your left foot out to the left (b), followed by your right, keeping tension on the band and your feet pointed forward. Take 10 steps, then switch directions and repeat on the other side.


3. Squat

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Start with a mini band positioned just above your knees and stand with your feet shoulder-width apart (a). Push your hips back and bend your knees to lower your body as far as you can, driving your knees outward against the band's resistance (b). Pause, then slowly push back up to the starting position. That's one rep. Do 15 to 20.


4. Knee Raise

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Position a mini band around the toes of your sneakers and under your soles and stand with your feet hip-width apart, hands on your hips (a). Lift your left foot off the ground to bring your knee up to hip level, keeping the band around your sneaker and your foot parallel to the floor (b). Pause, then return to start and repeat on the right side. That's one rep. Do 10 to 12.