内六角圆柱头螺钉是一种常见的紧固件，其规格种类丰富，根据国家标准GB70-1985进行划分。常见的尺寸系列包括以下几种：

3mm*8mm

3mm*10mm

3mm*12mm

3mm*16mm

3mm*20mm

3mm*25mm

3mm*30mm

3mm*45mm

4mm*8mm

4mm*10mm

4mm*12mm

4mm*16mm

4mm*20mm

4mm*25mm

4mm*30mm

4mm*35mm

4mm*45mm

5mm*10mm

5mm*12mm

5mm*16mm

5mm*20mm

5mm*25mm

6mm*12mm

6mm*14mm

6mm*16mm

6mm*25mm

8mm*14mm

8mm*16mm

8mm*20mm

8mm*25mm

8mm*30mm

8mm*35mm

8mm*40mm

以上尺寸是内六角圆柱头螺钉的常见选择，实际应用中，您可能还会遇到其他非标尺寸，但在工业和建筑领域，这些标准尺寸能满足大部分常规需求。在选择螺钉时，请确保其与您的应用环境和设备匹配，以确保紧固效果和安全性。