There are a few types of pull up assistance bands on the market, and each has its own advantages and disadvantages. 

The first type of band is the loop band. Loop bands are the simplest type of band and consist of a loop of elastic material that you attach to a bar above your head.

To use the band, you simply wrap it around your hand and pull up with your other hand. You can visit www.amonax.com/products/amonax-resistance-bands-assisted-pull-up-band-set-men-door-anchors-inc to buy pull up assistance band.

The second type of band is the strap band. Strap bands are similar to loop bands, but they have two straps that you attach to a bar above your head and then loop around your hands. To use the band, you simply slide your hands through the straps and hold on to the ends. 

The third type of band is the suspension band. Suspension bands are similar to strap bands, but they have a series of straps that hang from a bar above your head.

You adjust the straps so that they hang at different levels, and then loop them around your hands. This allows you to raise your arms higher than with a strap band or a loop band. 

The fourth type of band is the cable pulley system. Cable pulley systems are similar to suspension bands.