I'm not using any flow control on the PDB however I tried a couple different ones on the ATC and the SMC ones from AlliedElec.com are much nicer and have a fine adjustment.
SMC Corporation - ASN2-N01-S - Pneumatics - Flow Control/Muffler - Allied Electronics
1/8" NPT Control Valve is #70072071
1/4" NPT Control Valve is # 70072072
1/4" NPT Swivel 90 x 1/4" tubing is 70070356
1/4" NPT x 1/4" tubing is 70070335
You can get the push to connect fittings anywhere, enco, ebay... They are 2 to 3.00 each.