What do PAR lamps and rebar have in common?

[65535]

They both feel really bad when they hit you in the head?

 

[derekleffew]

Both diameters are measured in 1/8".

Ten minutes after I posted the question, gafftapegreenia provided the answer I was looking for. To allow more discussion, I hid his post until now.

 

[venuetech]

lamp diameters in general are measured in 1/8"

 

[mstaylor]

Rebar is ordered by size, #4 rebar is 1/2 inch.

 

[epimetheus]

...they both light up when you have enough electricity running through them!

I like this answer best.

 

[mstaylor]

They both feel really bad when they hit you in the head?

My favorite answer, wrong but darn funny.

 

[65535]

I should mention they are also great for hitting other people in the head.

 

[TheDonkey]

My favorite answer, wrong but darn funny.

Not wrong per-se, just not the answer they were looking for.