What also as comfort on the flash recharge time, on my Canon 580EX going from 5-6 sec to less than 2 sec for flash charging to 1/1 power and on my Yongnuo YN560II full power is one 1sec to reload, the only downside is if abused the flash will rapidly overheat (15-20 lightning daffilée without installation).
If the product is of good quality, plastic does not do "first prize" the cover is handy to attach it to the foot of the flash by its strap, and a light comes on when the case is on and the cable seems to good quality.
Very good product for the price.