Some of the models we offer will require a "break-in" period. Straight out of the package the grips may feel slippery, however, this is normal. The outer material of the grips needs to be roughened up in order for the fibers to start producing friction.
Using chalk and friction for the first few sessions is the easiest way to break your new grips in. You may also use wire brush or bar knurling to do this until you can see the texture of the pad becoming rough.