I have this on my 7.9 gallon speidel and it fits great. I’m using a metal dip tube with thermowell attached to a ball valve.

Hi Daniel - The mentioned gasket is not compatible with the 7.9 gallon fermenter. If you have any additional questions or concerns please contact us by phone or email.

Hi I can't answer this question since they are mounted in the tanks and the tanks are full. I can say that they worked as advertised.

I do not know what the dimensions are but I do know that you need these gaskets if you are to use items #FE740 FE741 FE742 FE745 FE746. You will need a locking ring FE785. I use FE741 FE745 (2)FE772 and (2) locking rings from FE785 on my 15GA. Speidel plastic fermenter. I control my fermentation with an Inkbird and a blowoff tube.

I have to add the 3rd gasket OD 1-3/4 ID 1-1/4. I forgot about this one on my earlier reply.

I measure 1-3/4" OD and approximately 1-5/8" to inside of flange pocket in it's resting state. It's silicone so it stretches a bit to accommodate the flange. I use it on the thermo well adapter with no issue. One word of caution is to not overtighten or gasket will compress and rip.

I am not sure which gasket one is OD 1-5/8 ID 1-3/8 the other is OD 1-1/4 ID 1. I have the original that came with the plastic spiget and then got the other when i ordered the racking arm.