Studio mod. 155 knitting machine is a bulky-gauge (its 110 needles are 9 mm apart) machine. This is the only bulky machine with punchcard capabilities released by under Studio/Silver Reed/Silver/Singer/Empisal model names. The punchcards are capable of creating 12-stitch repeat patterns. Its simpler sisters are Studio mod. 150 and 151 machines, while its more complex cousins are the 890 models by Silver Reed.

It accepts 12-stitch punch cards to make needle selection automatic to knit various patterns (in combination with carriage settings).

Patterning is achieved through the typical-for-Studio-machines patterning drums.

Matching add-on accessories are Studio SR155 ribber (as well as Empisal Knitmaster SR155, Silver Reed SR155, Singer SR155), Knit countours KR6, KR7, KR10, and KR11, and intarsia carriages AG30, and AG155 (this one is also a plating carriage).

It is a very popular and sought-after machine because of its bulky gauge and simplicity (electronic machines are sometimes finicky and too comples for some users).
PROS AND CONS:
PROS:
- bulky-gauge: accepts thicker yarns and fibers for hand-knitting;
- simple to use;
- has add-on accessories to diversify its use;
- accepts punchcards (unlike basic/manual Studio mod. 150 and 151 models) for easier patterning and needle selection
- very robust
- Replacement parts are available on the new and used market
- if you find blank 12-stitch punchcards, it is easier (than 24-stitch ones) to make patterns: fewer holes to punch out
- good resale value
CONS:
- only 12-stitch patterns (Broher KH260 takes 24-stitch cards). However, 12-stitch patterns on bulky knits look better anyway. The stitches are already big, so the pattern with wide repeats might get lost. So, I do not consider it a big cone like other knitters.
- patterning with drums: yarn and lint get tangled in them quite often; they also freeze when not in use for a long time.
I do have this machine in my stash, so stay tuned for first-hand insights.

