West Hill Wagon Works TT Gauge TT:120 Lineside Gradient Sign Posts (Pack Of 8)

Gradient sign posts
Supplied in a packs of 8 sign posts with a variety of gradients 
TT:120 Scale
The numbering on each post is slightly raised to allow it to be picked-out in black on each sign post.

Gradients on the railway are rarely constant over any considerable length, and may change several times within the space of a mile.
Gradient signs were first used around 1850 with a sign placed at each location where the gradient of the line changes. Most gradient sign posts located on the lineside have two arms facing the track, one on either side of a post. The arms slant up or down to indicate the direction of the gradient, and have the gradient marked on them.
The gradient is expressed as a ratio, e.g. "1 in 200" (or "1:200")that means that the track rises (or drops) one unit for every 200 units travelled horizontally.
1 in 200 is therefore a steeper gradient than 1 in 500.
Some designs of gradient sign post do not show the first part of the ratio so 1 in 200 is shown merely as “200”.
In general gradient sign posts are painted white with black lettering, however from the 1970s onwards some are painted yellow.