As a self defense pressure point, there may be an effect, but good luck using it! This is more of a healing point than a Dim-Mak point. It is also used to produce and to improve the quality of breast milk.

SI-02:
When a loose fist is made, the point is distal to the metacarpophalangeal joint, at the junction of the skins colour change from the Yin/Yang perspective.

This is a great finger lock pressure point for control of an attacker in a hands-on situation. There are long term health affects like Heart issues, and general poor health. However, these are unlikely in a real street situation.

 
SI-03:
When the fist is loose, this pressure point is located proximal to the head of the 5th metacarpal bone on the ulna side, in the depression at the junction of the red and white skin. Lateral to the abductor digiti minimi manus.

This pressure point is very hard to strike, but considerable damage does result! Perhaps you have broken a brick with the knife hand and hit this pressure point? This is a great pressure point for a finger lock and has an adverse effect on the Liver if damage is untreated.  As a Confluent Pressure Point activation weakens the neck and shoulders.

SI-03 is also a Confluent Pressure Point and an is an Underlying Indicator Point.

SI-04:
The location is on the ulna bone side of the palm, in the depression between the base of the 5th metacarpal bone and the triquetral bone. Lateral to the origin of the abductor digiti minimi manus.

This pressure point also has some devastating effects on the body, but is almost impossible to access. The immediate effect is energy loss. Heart and Gall Bladder problems are possible long-term effects.

This is a healing pressure point for Gall Bladder.

SI-05:
SI-05 is located on the ulna bone side of the wrist, in the depression between the styloid process of the ulna and triquetral bones.

This pressure point is an excellent “set up point” for a more dangerous strike such as to ST-09, SI-16, ST-15, or CV- 14. All pressure points listed can cause death when SI-05 is first activated.

SI-05 is an Underlying Indicator Point.

SI-06:
Located dorsal to the head of the ulna. When the palm faces the chest, the pressure point is in the boney cleft on the radial side of the styloid process of the ulna. On the dorsal aspect of the ulna, above the head of the ulna at the wrist, between the tendons of the extensor carpi ulnaris and the extensor digiti minimi manus muscles.

This pressure point has been known to cause temporary blindness.

SI-07:
This pressure point is located 5 cun proximal to the wrist, on the line joining SI-05 and SI-08. This is the first of several dangerous Small Intestine pressure points. 

Attacking this pressure point can have an influence on the Heart, cause nausea and possibly a knockout. Legend has it this pressure point can cause permanent blindness. Use caution always!

SI-07 is a Collateral Pressure Point and is an Underlying Indicator Point.

SI-08:
Located with the elbow flexed, SI-08 is located between the olecranon of the ulna and the medial epicondyle of the Humerus. 

This is a very dangerous pressure point to strike. Aside from the fact that it will cause considerable pain and Chi drainage, if struck at the same time as LU-05, it will cause a knock out or even possible death.

SI-08 is an Underlying Indicator Point.

SI-09:
As you can see in the image below, SI-09 is located posterior and inferior to the shoulder joint. When the arm is adducted, this pressure point is 1 cun above the posterior end of the axillary fold, at the lateral margin of the scapula below the Infraglenoid tubercle.

A solid strike to the area will cause an immediate rush of energy to the head resulting in great nausea, fainting, and a build up of stagnant Chi at the base of the skull at GB-20. The result feels like the head is exploding.

SI-09 is an Underlying Indicator Point.

Number 11 is the Infraglenoid tubercle location

SI-10:
When the arm is adducted, this pressure point is directly above SI-09, in the depression inferior and lateral to the scapular spine. In the deltoid muscle posterior to the glenoid fossa of the scapula, and in its deep position, in the infraspinatus muscle.

Due to its position on the shoulder, a great amount of physical damage will result when this pressure point is struck hard. The damage is so great it will often cause a knockout to prevent serious damage to the shoulder blade or scapula. The damage to the area will be extensive rendering the arm useless.


SI-11:
Located in the infrascapular fossa, at the junction of the upper and middle third of the distance between the lower border of the scapular spine and the inferior angle of the scapula. In the infraspinatus muscle.

This pressure point is a major strike target on the back of the body. A solid strike will immobilize the entire arm due to Chi drainage. Often times a medium palm strike can have a BIG effect. There will be an electrical shock sensation down the arm.

SI-12:
The pressure point is located in the centre of the suprascapular fossa, directly above SI-11. When the arm is lifted the point is at the site of the depression.

A strike here will cause an energy rush to the head and a likely knockout. The entire upper body will fee “odd” from the hit. Often times damage to the scapula and related parts will result including dislocation.

 
SI-13:
SI-13 is located on the medial extremity of the suprascapular fossa, around midway point between SI-10 and the 2nd thoracic vertebra of the spine and on the superior margin of the spine of the scapula, in the trapezium and supraspinatus muscles.

A medium to hard strike can damage the scapula as well as the Lungs. The effect from a Kyusho standpoint is a complete feeling of energy drainage and the inability to continue the altercation.

SI-14:
This pressure point is located 3 cun lateral to the lower border of the spinous process of the 1st thoracic vertebra, on the vertical line drawn upwards from the medial border of the scapula.

Striking this pressure point will shock the upper body and can cause both the Heart and Lungs to fail. Extreme nausea will result with violent vomiting and possible death if left untreated. This is a very dangerous pressure point especially if used with CV-14.

SI-15:
Located 2 cun lateral to the lower border of the spinous process of the 7th cervical vertebra (GV-14). At the end of the transverse process of the 1st thoracic vertebra, superficially in the trapezium and in its deep position, in the levator scapulae muscle.

A strike will result in nausea and a possible knockout if it is hard enough. There will be some nervous system damage due to the proximity to the spine and neck.

SI-16:
SI-16 is in the lateral aspect of the neck, on the posterior border of the Sternocleidomastoideus muscle, posterior to CO-18, 3.5 cun lateral to the laryngeal prominence.

 
Striking this pressure point will often cause the person to laugh, however the possible resulting damage is nothing to laugh at! If struck on the left side of the body hard enough it can stop the Heart resulting in death. A lighter strike can cause Heart issues in anyone with a disposition to Heart problems. Sometimes this pressure point is used in knockout demonstrations, but this is fool-hearty as death can result.

Save this pressure point for life and death situations! SI-16 is also one of the 36 Dim Mak Vital Points

SI-17:
SI-17 is located posterior to the angle of the mandible, in the depression on the anterior border of the sternocleidomastoideus muscle and the inferior margin in the posterior belly of the digastric muscle.

Again, this is a very dangerous pressure point and should not be played with! This pressure point is very close to the vagus nerve and will cause a knockout quite easily due to a drop in blood pressure. Therefore making it very dangerous!

 
SI-18:
This pressure point is located directly below the outer canthus, in the depression on the lower border of the zygoma, level with CO-20.

Best attacked with a small penetrating weapon like a single knuckle. This pressure point will cause a rush of energy to the brain causing a knockout.

 
SI-19:
SI-19 is located between the tragus and the Temporomandibular Joint, where a depression is formed when the mouth is slightly open. At the anterior of the middle of the tragus, and the posterior margin of the condyle of the mandible.

This pressure point is said to cause a knockout, however I have not seen or done one using this point. It does affect up the sinuses and can cause ringing in the ears.