This is the widest door frame pull up bar, the only one to accommodate 40" doorways and can also be used in narrow passage ways
The rubber hand grips move off center when the bar is extended (as per image), though they can be moved this is not the easiest to do and there are reports of it bending under heavy weight when extended to widest lengths
Great for wide door frames / narrow passage ways if you're not near the weight limit of 250 lbs
The JFit deluxe pull up bar is a single bar which fits in your doorway by either sitting in the safety cups which are screwed to either side of the doorway or simply by the friction created from twisting it to tighten against the door frame. With these type of bars the manufacturers always recommend you use the safety cups (I think mainly to avoid law suits), however many people use this bar without the safety cups and the need to screw fixings, however if you do you'll need to make sure you've re-tightened before each use otherwise it may slip over time.
The way this bar is designed, when you tighten it one side extends rather than both, this means that the hand grips will move off center of the doorway (as per the product image), however JFit have said that all you need to do is leverage under the grips to break the vacuum seal and they can be moved to a different position to suit, though this may be a bit fiddly.
This bar fits the widest range of doorway widths from 26" to 40" (66cm - 101.5cm) and can even be used in narrow passage ways, but beware the wider you extend the bar the more likely it may bend if your weight is approaching the supported limit of 250 lbs (133kg).
This type of bars only come with the padded grips for a single grip position, this can be used for either chin ups to work you arms or pull ups in a neutral position to work your arms and back.
View an online version of the JFit Deluxe Doorway Pull-Up Bar manual