Vac pipe Brass insert

[Theclash]

Changed the vac pipe on choke pulldown unit and got the tiny brass insert out of the old pipe , on closer inspection there seems to be a hole at the larger end and no hole at the other end is this right cause how can it suck any vacuum ?
I left it out of the new pipe and once fitted and fired up the throttle flap operated as it should ie 3mm gap which it as never done with the old pipe fitted
Anyone any idea if there should be a hole at both ends of the brass fitting

[kevtherev]

The restrictor smoothes out the flap operation
It stops the engine hesitating/stalling under choke conditions by stopping the flap snapping open under acceleration on full choke.