Please recommend a home in the abdomen exerciser

similar to the barbell arm strength or the same device can be placed on the convenience of home abdominal exerciser

trouble say a few words of equipment name (easy to find online) and the price

Thank you

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Bed .

In bed can do many sports, ah. Such as "sit-ups" (legs fold flat. Do not hold him down leg, and then renewed), and one was lying in bed, legs close together, lift, and body into a 45 ° (Forget What's the name of), You can insist on the extraordinary 啦 3 minutes, but also the other what to do