Bollfilter UK in your pocket offline. Crucially the Internet is not always available, so our “BOLLFILTER UK APP” works offline without the need for the internet except for: YouTube Videos, updates and the “contact us for assistance features”. It is information when you need it when you’re off grid. So we decided it was time to put most of the information that Technical people and Engineers want into one small piece of Software called the “BOLLFILTER APP” with a strap line that is “Bollfilter in your pocket”. This is for your iPhone or iPad.