I like these extensions so that you can adda 2nd keyboard on top but they do lack some adjustments. If you are fussy (like me) about exactly where the top keyboard sits then you may need to get get a bit physical with these and mangle them to suit your needs. I ended up hacksawing off about an inch or 2 of the arms so the top board sat a little further back and added some new bolts as restraints to stop it falling off. It is a bit of a hassle to do that with a brand new product that you have just bought but there was no alternative for me. If there had been more adjustments possible I may not have had to do all that.
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