.033uF (.033 mfd) Metallized polyester non inductive capacitor. This is the famous Mallory® Mustard Cap. Its small physical size and axial style leads make these caps a pleasure to use in guitar circuit wiring. 5% tolerance.
This cap is an in-between value. Why use a .033 tone cap? The .047 gets things pretty dark, maybe too muddy. But then again, if a person wants to wah-wah or women tone, that's the way to go. The .022 would be quite a bit brighter. The .033 gets you in the middle naturally and strikes a good compromise between both worlds.
Professional installation is strongly recommended. Improper installation may result in damage to the product and/or instrument.