seventh

In the second position because that's where the first finger is but it's best found by placing this important movable shape on the 5th fret with your little finger.

An important chord when playing a blues in G because the tritone defines the chord well, the 5 in the bass is a bonus and you can get away without the tonic.

A good voicing for a 7th chord that forms the basis of an important moveable shape.

An important voicing with the root in the bass and the tritone on top. When playing a blues in G you need to wear this one out.

Based on the 2nd position barre chord the b7 note is the open G on top. Note that there is no 3 though so you can't make a tritone and you lose the essence of the 7th chord. An easy shape though and it can still be useful for quick chord changes.

A bit of a squeeze this far up the neck but some guitars will manage it just fine. 

One of my favourite moveable shapes with the tritone prominent up top and the 5 in the bass. In the 10th position its F7

The root in the bass and the tritone on top this is a good one.

With the 5 in the bass and the tritone on top this is one of the better options for a 7th chord, a good moveable shape to learn.

A useful voicing with the tritone on the top and the 5 in the bass works well in a blues and is a handy moveable shape.