Block

High/Rising Block

1) Lead Arm *Hopkins example *example *example

Outside Block

1) Lead Arm  *example *example

2) Rear Arm *example *example

(The following are almost exclussively used against weapons)

Inside Block

Down Block

1) Lead Arm

2 Rear Arm

Cross Down Block

Notes: 

I generally favor covers over long arm blocks. In theory, long arm blocks have the advantage of reducing or even eliminating concussive force transmission to the head that commonly occurs when defending with covers. Because long blocks intercept punches farther from the skull, the arm absorbs impact energy. With covers, the hands connection to the head means some of the blows impact energy will travel through the forearm into the head.

However, while this style provides stronger protection against concussive trauma in concept, it also demands a superior ability to recognize and react to specific attacks. Additioanally, the arms are further away from the head leaving it exposed if the if the opponent manages to bypass or slip around the extended arm

If I does use long blocks, it is when I can (or try to) keep the fight at long range. When things are tighter, I go to covers. 

A key reason to train long arm blocks is their necessity when defending against weapons such as clubs or knives. In real-life confrontations involving armed attackers, tight covers are rarely effective at intercepting slashes, thrusts, or heavy swings, since the arms must actively meet the weapon at distance to prevent it from reaching the body or head. Long blocks allow you to create space and protect vital areas.

Knife Defense Simplified: Essential Techniques For Everyday Safety