It's not everyday that you see kit manufacturers appear as the main sponsor, too. But throughout history, many club kits have featured the maker at the very centre of their shirt as well as on the chest. 
When it comes to the lack main sponsor, the most memorable example of all in recent times is Barcelona who went without a sponsor up until the 2006-07 season, then once again in 2016-17 when they parted way with Qatar Airways.
However, with smaller clubs (and smaller manufacturers), the centre slot for sponsor is a vital. Which is why we sometimes see examples like below.
This would last well into the first decade of the 21st century until 2009 when Bolton got 188Bet as the main sponsor.

Reebok would remain as manufacturer for three seasons before Adidas took over.

In 1997, Puma would have their logo placed on both the right side of the chest and at the centre.
From 98-99, however, EDS took over the main sponsor slot and stayed there until 2001.

But it wasn't until almost 20 years later that Celtic would have Umbro as both their manufacturer and main sponsor.

This would last for two seasons, from 1997 to 1999 but Umbro remained as manufacturer for another seven years.
Those were some of the prime examples of kit manufacturers acting as main sponsor on the shirt. Other clubs have also done this before when no sponsor was found.
Which one was your favourite manufacturer + main sponsor partnership? Share your thoughts below.
Manufacturer 🤝 Sponsor
— Classic Football Shirts (@classicshirts) November 7, 2021
Can you think of any more teams that had their shirt manufacturer sponsor their kit? pic.twitter.com/QHarVFioca
Kits With Manufacturer As Main Sponsor
Having a sponsor on the front of the shirt is crucial for any club for decades. It generates a great deal of money for the club.When it comes to the lack main sponsor, the most memorable example of all in recent times is Barcelona who went without a sponsor up until the 2006-07 season, then once again in 2016-17 when they parted way with Qatar Airways.
However, with smaller clubs (and smaller manufacturers), the centre slot for sponsor is a vital. Which is why we sometimes see examples like below.
Bolton Wanderers x Reebok
Perhaps the longest manufacturer + sponsor partnership of all time. Reebok appears on Bolton's shirt at the start of the 90-91 season.This would last well into the first decade of the 21st century until 2009 when Bolton got 188Bet as the main sponsor.
Reebok would remain as manufacturer for three seasons before Adidas took over.
Derby County x Puma
Puma became the manufacturer for Derby in 1995. For the first two seasons, they would appear at the centre of the shirt, right below the crest.In 1997, Puma would have their logo placed on both the right side of the chest and at the centre.
From 98-99, however, EDS took over the main sponsor slot and stayed there until 2001.
Celtic x Umbro
Umbro's relationship with Celtic dated way back to the 1978-79 season.But it wasn't until almost 20 years later that Celtic would have Umbro as both their manufacturer and main sponsor.
This would last for two seasons, from 1997 to 1999 but Umbro remained as manufacturer for another seven years.
Udinese x Lotto
Moving out of the UK mainland, we found Udinese and Lotto in the 2008-09 season. In the span of their five years partnership, Lotto appeared once at the centre of the shirt.Those were some of the prime examples of kit manufacturers acting as main sponsor on the shirt. Other clubs have also done this before when no sponsor was found.
Which one was your favourite manufacturer + main sponsor partnership? Share your thoughts below.