ISO 3601-4:20 08规定了五种类型的抗挤压环（也称为支撑环）的尺寸和公差: 螺旋型（T1）； 角切型（T2）； 固体型(T3)； 切角凹型（T4）； 实心凹型（T5）。 这些防挤压环用于ISO 3601-1中规定的选定O形环尺寸和ISO 3601-2中规定的相关外壳尺寸。

ISO 3601-4:2008 specifies dimensions and tolerances for five types of anti-extrusion rings, which are also known as back-up rings:

1. spiral type (T1);
2. angle cut type (T2);
3. solid type (T3);
4. angle cut concave type (T4);
5. solid concave type (T5).

These anti-extrusion rings are for use with selected O-ring sizes as specified in ISO 3601-1 and the relevant housing dimensions specified in ISO 3601-2.