I suggest that you get the B model (0-60psi gauge) VTS250 series if you are using a diffuser that requires up to approx 30 psi and also use it for general all around use. I like the A model (0-30psi gauge) because I use low pressure diffusers. The C model (0-100psi gauge) will still work fine, but I prefer the A or B models over the C models. The D model (0-200psi gauge) will also work, but it offers less control in the lower psi range. In other words, for our use, the preference order goes like this: B - A - C - D . (My preferential order is: A - B - C - D .) I usually look for the VTS253 models over the VTS250 and VTS252 models. The VTS253 models are a newer release.
outlet pressure ranges reference: http://victortechnologies.com/IM_Uploads/DocLib_2310_56-0623 VTS 250 Series Regulators.pdf
(0-30psi gauge): 2-15psig
(0-60psi gauge): 2-40psig
(0-100psi gauge): 4-80psig
(0-200psi gauge): 5-125psig
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outlet pressure ranges reference: http://victortechnologies.com/IM_Uploads/DocLib_2310_56-0623 VTS 250 Series Regulators.pdf
(0-30psi gauge): 2-15psig
(0-60psi gauge): 2-40psig
(0-100psi gauge): 4-80psig
(0-200psi gauge): 5-125psig
[attachment=1423:name]