heel side meaning in English

背缘
脚根边

Choose the proper size and shape able to put one finger at heel side the front should be roomy enough for the toes to lie flat and wiggle , but it should not be too wide , otherwise the friction will cause calluses the material should be soft , breathable and flexible
鞋码适中，鞋内留一横指的空间鞋头质料宜软宜圆宜宽，能让所有脚趾平放和略为活动但不宜过宽，因会增加皮肤的磨擦而生厚茧。
Choose the proper size and shape ( able to put one finger at heel side ) the front should be roomy enough for the toes to lie flat and wiggle , but it should not be too wide , otherwise the friction will cause calluses the material should be soft , breathable and flexible
鞋码适中，鞋内留一横指的空间；鞋头质料宜软、宜圆、宜宽，能让所有脚趾平放和略为活动；但不宜过宽，因会增加皮肤的磨擦而生厚茧。