SDS hammer/drills - what does the spec "1 inch" mean?

[Stephen Tashiro]

Models of the Bosch Bulldog SDS hammer are advertised as "1 inch" or " 1 1/8 inch". What do those dimensions refer to?
-obviously not to the diameter of the bit shaft since the following examples both take "SDS plus" bits.

https://www.lowes.com/pd/Bosch-Bulldog-Xtreme-SDS-Plus-8-Amp-Keyless-Rotary-Hammer/1082989


The Bosch 11255VSR 1 In. SDS-plus® Bulldog™ Xtreme Rotary Hammer is a versatile, handy tool


https://www.lowes.com/pd/Bosch-Bulldog-Xtreme-Max-SDS-Plus-8-5-amp-Keyless-Rotary-Hammer/1000163219


The Bosch GBH2-28L SDS-plus® Bulldog™ Xtreme Max 1-1/8 In. Rotary Hammer features a powerful 8.5 Amp motor and KickBack Control.

[Ron Selzer]

I always understood that to be the max size solid bit you should use with that drill. They are rated for larger hollow bits
Ron

[Rich Engelhardt]

It refers to the maximum hole size the tool can drill in concrete.

Edit - Ron said it more clearly. The maximum solid bit you should solid use - not can use. You can use a 1 1/8" solid bit in a 1" SDS, it will just shorten the life of the tool.

[Frank Pratt]

Yes, it refers to the largest bit that should be used in concrete. But it's just a rough guide because there are so many variables with hardness, type of aggregate, etc. I have Milwaukee's smallest M18 rotary hammer & it drills 1-1/8" holes in block like it's butter, not so much in hard concrete.

[Bill Dufour]

FYI My Hilti SDS+ is rated, in old concrete?, with a 1/2" bit at 18" per minute. I know a bigger bit will slow the rate of penetration.
Bill D

[John Stankus]

I picked up a GBH2-28L earlier this year after a neighbor knocked down my stone mailbox. Love the thing. After years of wearing holes in concrete or stone with a regular drill (always felt like it took years to bore a hole :) ). A rotary hammer is awesome for concrete holes. And it was fun using the chisel to remove the stone mailbox residue. I went with the slightly more expensive one for the vibration control.

John