I'm not sure if I have the right sizes but this is what I measured them as right from the rebuild kits if anyone can confirm, correct, or complete this list by all means go ahead. All O-rings are 90 Durometer Urethane (except where they are listed as Teflon).

Classic Valve (for Automag 68 and Mini-Mag; 1 rebuild)
4 Power Tube O-rings 010
4 Teflon O-rings 006
2 Barrel O-rings 018
2 Reg. Piston O-rings 012
1 Reg. Body O-ring 116

RT Classic (1 rebuild)
3 Field Strip Banjo O-rings 009
3 Barrel O-rings 018
2 Power Tube O-rings 010
1 Reg. Piston O-ring 012
2 Reg. Seat O-rings 008
1 Reg. Body O-ring 018
2 RT On/Off Small O-rings 004
4 RT Reg. Valve Pin O-rings 006

Level 10 Bolt (1 install)
2 Carrier O-rings 008
1 Power Tube Tip O-ring M1.78X7.94?!? (I need to confirm this. Is this the same Size as would be found on other mag valve tips? I had a dead one in an old Mini-mag that I couldn't figure out the size for, but I replaced the Level 7 with a Level 10 and didn't need it anymore.)

X-Valve (for RT-Pro, RT Custom, Emag, and Xmag; 1 rebuild)
2 Power Tube O-rings *
1 Reg. Piston O-ring *
3 RT Reg. Seat O-rings *
1 RT Reg. Body O-ring *
2 RT On/Off Small O-rings *
4 RT Reg. Valve Pin O-rings *
5 L10 Carrier OD O-rings *

Emag On/Off O-Ring (sold Seperate from the kit above)
4 Emag On/Off O-ring * Quad (this is a special O-ring that does not have a circular cross section, the cross section looks more like an X)

Flatline Reg (for Flatline 3000 psi and 4500 psi Tank Regs)
1 Body O-Ring *
1 Seat O-Ring *
2 On/Off Cam O-Rings *
1 Piston O-Ring *
1 Small O-Ring *
1 Tank O-Ring *

* I don't know the size for these at this time (mostly because I don't own them).