Prusa i3 MK2 Filament Filter with 4mm PTFE tube

I got this design idea while using cocoknight's snap-on filament filter ( http://www.thingiverse.com/thing:2086804 ). It's well designed but I've different usage requirement.

I need a filament filter that able to:
1. Snap-on top of Prusa i3 MK2 extruder, but easily remove-able.
2. Able to put an 4mm PTFE tube into it.

So this is what design I came out with.

I use idler as snap-on point. It seat secured enough as filament movement will push it downward naturally. And it's easily remove