do yourself a favor and save yourself the 90 + dollar . this thing be a flimsy , cheap plastic piece of junk that rely on the pressure of two plastic piece , compress together to keep itself attach to you chair . I be very excite to try this out , since I renovate my office a bit and remove my formal desk , and now need a place to rest my kbd and mouse . talk about depressing . the box it come in have better production value . first , the keyboard tray be completely separate from the rest of the mount item , so at any second the thing be bump , jiggle , or downright fall off during normal movement . not to mention it be literally a black piece of plastic no better or bigger than the smallest , cheapest cut board you could buy for you kitchen . next , the armrest mount , when mount evenly have a little piece that fit inside in order to adjust for the curve of you chair armrest . this piece will fall out with hardly any provocation . also , the bracket that hold the front and back in place be do so with screw - that 's right - it be not like they be adjustable , smooth piece that snap into place like you would expect - you literally have to take these small rough edge bracket and screw they into the bottom of the armrest cover . and because you be simply hold they in place with pressure - guess what - any bump against the back of the armrest cover and the whole thing slide forward dump everything in the floor . oh and do I mention that if you use this on a chair with a wood frame you just scratch the hell out of the wood ? yea - you do . additionally , the armrest sit in so far that unless you have a super-sized chair base , or be anorexic , you can expect to not be able to spread out , or sit as comfortably as you like , or on some chair , literally have this thing dig into you . I could see where you basic , run of the mill , 30 dollar office chair with a short back and tiny armrest would probably do ok with this thing -lrb- but then , why would you need it since you would probably have a desk to go with that kind of chair -rrb- , but for 90 dollar - I mean really - 90 buck ?? - you would be better off get one of those laptop station with the beanbag bottom that fit in you lap for half the price . I literally put this thing on three different chair , test each one for a full hour or so of normal operation , and throw it back in the box . mobo should be ashamed of themselves for put such a price tag of this crap . this be not worth it , but spend you money how you want .