These are all water gauges for live steam boilers. all come complete with glass, nuts and nipples. Made in the UK

3/16 x 40 glass is 1 5/8" long in between centers

1/4 x 40 and 1/4 x 32 are both 2 1/4" long in between centers

5/16 x 32 and 3/8 xx 32 are both 2 1/2" long in between centers