Something I discovered quite early when playing acoustic slide guitar is that the slide itself makes a big part of the sound. A brass slide will give a beautiful metallic ting. This is worth well the investment. The inner diameter is not too big. It works well for the pinky - might be too small for the index though. I like the slightly conic shape which (I find) gives greater control and precision than plain cylinders. Two disadvantages - which you get used to after a while: it's heavy - you feel the weight after a while, and it's also thick brass metal, so you do feel the cold on your finger...