Pump it up! Inflatable rubber dildos and plugs are a good and gentle way to increase the size of what you can take. The line of inflatables that we carry is top of the line. The rubber is approximately 2 mm thick, they're glued together very carefully and we use high quality metal valves.
As for any insertable toy: use lubricant. Because these inflatables are made of natural latex: do not use oil based lubricants because these will deteriorate the rubber.